The Planetside 2 system requirements are incoherent nonsense, most likely written by someone who knows little about computer hardware and was just guessing. So I'd ignore them and just get a good gaming rig.
besides PS2 of course, a Few smaller games, and the Regular stuff I dont plan to need 2 much space..
BUt can you tell me why your build is so much cheaper then the other before you? Is there something The other build had that was not needed?
I left out a monitor, which is a large chunk of the price difference.
Most of the rest is that I picked a much cheaper processor. The processor I picked has 6 cores rather than 4, but each core is slower, so they'll be roughly even in games that scale well to many processor cores, but an FX-6300 will lose by quite a bit to a Core i5-3570K in games that aren't able to put 6 cores to good use.
In many cases, there will be a measurable difference but with frame rates so high that the diffference doesn't matter. If one processor can get you 100 frames per second and another can get you 150, do you really care about that difference? What if, at the graphical settings you want to use, your video card limits you to 70 regardless of the processor, so you don't even see a real-world difference?
There will be a handful of badly-coded games where the Core i5-3570K really does give you better real-world performance than an FX-6300. But from a coding perspective, it's pretty easy to make games scale well to as many processor cores as you want (or at least a lot more than your game actually needs in order to perform well), so it's only a difference for badly-coded games. The only MMORPGs I'm aware of off hand where you're likely to see a difference are EverQuest II and Guild Wars 2.
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I actually picked a better quality motherboard than Recon. They're different processor sockets for different processors, so you can't just swap motherboards without swapping the processor.
We both picked a Radeon HD 7870. I picked a cheaper one. Recon was scared off by a single user review from someone who bought the one I linked and had it not work, so he decided to have you pay $20 more and give up a $15 rebate to get an equivalent card that also has some bad user reviews, but a lot more good user reviews.
Recon picked a power supply with a higher nominal wattage. I picked a power supply that is much higher quality. For the amount of wattage you're likely to pull (probably never over 300 W if you don't overclock), a Rosewill Capstone 450 W will deliver that power much better than a Corsair CX600 V2. Mine will have much better energy effiiciency and voltage regulation and uses higher quality internal components. Pulling 200-300 W under fairly heavy gaming loads isn't enough stress on a high quality 450 W power supply to be problematic. If you have ideas about overclocking everything to the moon and seeing if it fries, then my power supply could be more of a problem.
As for brand name, yes, an average Corsair power supply is better than an average Rosewill power supply. But a low end Corsair power supply certainly isn't better than a high end Rosewill one. (The Corsair CX600 V2 is actually made by Channel Well, while the Rosewill Capstone is made by Super Flower, so neither company actually manufactures their own power supplies.) It's kind of like saying that for Windows, an average Nvidia GPU is faster than an average AMD GPU. (This is actually true, largely because AMD still makes a lot of integrated graphics and Nvidia doesn't.) But that doesn't mean that a low end GeForce GT 520 is faster than a high end Radeon HD 7970; to the contrary, the latter is faster by more than an order of magnitude.
The memory and optical drive that I picked are equivalent to the ones Recon picked. But mine cost $2 less.
Recon picked a faster, smaller hard drive that is also a little more expensive. And a lot noisier. VelociRaptors have been basically obsolete for a few years now because Western Digital wanted to charge enough to buy a VelociRaptor that you could buy an SSD for that price and get something orders of magnitude faster. But at $70, I wouldn't be critical of buying one--though you should be warned that they're noisy.
We picked different cases. I think the case I picked is probably a little higher quality, but that's only a guess.
Recon wants you to waste $10 on aftermarket thermal compound. I say that's completely stupid. AMD's FX processors ship with a much better stock cooler than Intel's processors, so my build gets you much better CPU cooling even without spending $10 on thermal compound.
Recon picked Windows 7 while I picked Windows 8. It's the same price either way, so which you choose is a matter of personal preference.
An thanks for the help. Im looking to get alot of the parts within the month with left over money an picking up the few parts within the next few weeks.. Its a timly process but I wanted to make sure what I was getting.. Nothing is final simply cause I wanna get this right the 1st time if you know what I mean lol. $900 is really pushing It an I wanna make sure I dont buy something Im gonna regret.
Personally on your budget I would go with the AMD build Quiz linked, with the bIgger SSD ( 240G).
I built my brother something very similar and it runs like a champ. If you are willing to up your budget some for an I5 and a z77 motherboard then IMO it would be a bit better computer. But for your needs that AMD build will do everything you want it to do and more while staying in your budget.
You can always save an buy another monitor later, I would not try and include a monitor in an $800 build. Get a decent box, use what you have until you can budget for a better monitor.
My 2cp
Hopefully you have someone who can help or put this together for you?
An thanks for the help. Im looking to get alot of the parts within the month with left over money an picking up the few parts within the next few weeks.. Its a timly process but I wanted to make sure what I was getting.. Nothing is final simply cause I wanna get this right the 1st time if you know what I mean lol. $900 is really pushing It an I wanna make sure I dont buy something Im gonna regret.
Prices change, and parts that are a good deal today might not be a good deal a month from now. So don't just wait a month and then buy the parts off of some old list or you're nearly guaranteed to overpay by $50 or $100 or some such.
Not sure where the figure of >400 watts is coming from, but this is showing about 100 more watts than your estimate. I realize the CPU isnt a Black Edition and it doesnt allow to seperately add a 7200rpm & and SSD, but the difference there cant be much more than about 15 watts from what is recomended here. I'm guessing 475-ish would be about right with an SSD instead of 2 7200rpm's. You can throw the top of the line 450watt PSU at a machine that needs >450, but its going to fail early as well as cause random shutdowns, crashes, BSODs & similar turmoil.
Maybe their estimates are REALLY far off.. Im not sure. I'm going to dig around for real numbers on wattage draw for these components.
You do realize that the nominal wattage on a power supply is a marketing figure and not an engineering one, don't you? If Rosewill had decided not to be so conservative and called it a 500 W power supply without changing the internals a bit, would that make it magically able to deliver more wattage? A lot of power supply vendors do list inflated wattage ratings, so power supply calculators tend to overestimate how much wattage you actually need because they don't know if you're going to buy some piece of junk that will give off sparks and smoke if you try to pull anything with 100 W of the rated limit.
Can a Corsair CX600 V2 deliver more wattage while staying in spec than a Rosewill Capstone 450 W? Probably. How much more? There's a pretty good chance that the gap is less than 150 W.
A Radeon HD 7870 has a default PowerTune cap of 190 W. An FX-6300 has a TDP of 95 W, which is basically enforced by reducing turbo clock speeds if necessary. Thus, the two big power consumers are capped at a total of 285 W, so even an artificial stress test won't pull more than that. Real games will usually pull far shy of that, especially considering that it is exceedingly rare for a game to push six cores hard, as such a game would probably be unplayable on a dual core processor. So the CPU and video card added together will probably never pull 250 W in real world usage. There are a bunch of other random things that will pull a few watts here and a few watts there, but that probably won't add up to 50 W even.
Not sure where the figure of >400 watts is coming from, but this is showing about 100 more watts than your estimate. I realize the CPU isnt a Black Edition and it doesnt allow to seperately add a 7200rpm & and SSD, but the difference there cant be much more than about 15 watts from what is recomended here. I'm guessing 475-ish would be about right with an SSD instead of 2 7200rpm's. You can throw the top of the line 450watt PSU at a machine that needs >450, but its going to fail early as well as cause random shutdowns, crashes, BSODs & similar turmoil.
Maybe their estimates are REALLY far off.. Im not sure. I'm going to dig around for real numbers on wattage draw for these components.
Thats off. maybe they are trying to oversell a PSU?
I plugged his components into another site and came up with a min 300w psu with a recommended 350w PSU.
Either way a 450w psu for a system at stock settings is more than enough. IMO nothing wrong with getting more than you need. I personally would rather buy a gold / plat certified PSU at lower wattage than a certified/ bronze PSU at a higher wattage.
I personally use the seasonic 550w gold certified, and I overclock my I5 some.
Either way that newegg estimate is off, the site I used was calculating the cpu at 90% TDP to come up with 300w.
My rule of thumb on power supplies if you're going to use stock settings is to take the processor TDP + video card TDP + 100 W, and then get a power supply rated at more than that on the +12 V rail. In this case, the computation is 385 W, and the power supply I linked is 444 W. The power supply that Recon linked is 522 W.
I'm not disputing your brands of choice... only the systems wattage requirements. My point is that yes, since ratings are driven by marketing a 500w continuous could actually deliver 540watts max. but it also means that with RFI, heat, aging, etc it could also hit sags and fall to 480w intermittently. There are also wattage needs that you're overlooking. Each USB device thats plugged in is going to bump up the wattage need by about 3-4 watts each, so I estimated 5 devices (15watts) that need figured into tthe draw to allow for things like a keyboard, USB mouse, Headset, Cell or iPod charger & desktop speakers.
My total on a more trusted wattage calculator is showing this to be right at a 450watt draw for the AMD FX-6300 setup you're recommending (calculated with 5 USB devices, having the SSD/7200 setup and with no overclocking of the GPU or CPU). I just think that recommending at mimimum a 500w rated PSU would be a more responsible recommendation and allow a safer ceiling for unanticipated future draw increases such as overclocking the GPU via Catalyst software.
Each USB device thats plugged in is going to bump up the wattage need by about 3-4 watts each, so I estimated 5 devices (15watts) that need figured into tthe draw to allow for things like a keyboard, USB mouse, Headset, Cell or iPod charger & desktop speakers.
The USB 2.0 specification only specifies power delivery of up to 2.5 W. If you try to pull 3-4 W from a USB 2.0 port, bad things will probably happen. USB 3.0 bumps that up to 4.5 W. But again, that's only up to that amount, and USB devices will usually pull less.
And remember where I approximated the "various other things" as using up to 50 W? That includes USB devices.
Speakers usually have their own power source, rather than drawing power from a computer's power supply. So, incidentally, do monitors, routers, and printers. For that matter, anything that needs more than 2.5 W can't get it through a USB port unless it's USB 3.0 only.
Originally posted by Recon48 I'm not disputing your brands of choice... only the systems wattage requirements. My point is that yes, since ratings are driven by marketing a 500w continuous could actually deliver 540watts max. but it also means that with RFI, heat, aging, etc it could also hit sags and fall to 480w intermittently. There are also wattage needs that you're overlooking. Each USB device thats plugged in is going to bump up the wattage need by about 3-4 watts each, so I estimated 5 devices (15watts) that need figured into tthe draw to allow for things like a keyboard, USB mouse, Headset, Cell or iPod charger & desktop speakers.
I use more or less the same thumbrule (TDP of CPU/GPU + 100W). That 100W is more than enough to cover USB devices, hard drives, motherboard devices, sound cards, fans, water pumps, and any other ancillary devices you want to include. It would take a lot of fans or hard drives, and a whole lot of USB mice/headsets/keyboards, to require bumping that number up significantly.
If a 500W power supply sags to 480W intermittently , that is a bad power supply. Whatever reason or rationale you want to throw at it, it still boils down to a bad power supply. A good power supply, on the other hand, will deliver 100% of it's rating, even if the wall voltage sags, or it starts to overheat, or starts to age, or whatever - and if it hits a condition where it cannot deliver 100% of it's rating, it should shut down rather than try to fry your electronics (probably due to either an overcurrent limiting device, or thermal protection shutdown). Most good power supplies actually do this - the problem is that most power supplies are not good, and most PC review sites aren't in-depth enough to be able to tell if they can do this or not, because testing for this kind of stuff is difficult and requires some rather sensitive and expensive equipment.
Coincidentally, the Wattage won't sag in your exmaple, it will remain constant because that's dependent on the load. The Voltage will sag, but since the load remains the same, the Current must go up by the same factor (by the electromagnetic definition of a Watt). By a correlating law of physics (Joule's Law), as the current goes up the heat goes up by a power of 2. This is why bad power supplies are so bad, and why voltage ripple, and to a greater extent, voltage brownouts, are such major electronic killers.
Originally posted by Recon48Each USB device thats plugged in is going to bump up the wattage need by about 3-4 watts each, so I estimated 5 devices (15watts) that need figured into tthe draw to allow for things like a keyboard, USB mouse, Headset, Cell or iPod charger & desktop speakers.
The USB 2.0 specification only specifies power delivery of up to 2.5 W. If you try to pull 3-4 W from a USB 2.0 port, bad things will probably happen. USB 3.0 bumps that up to 4.5 W. But again, that's only up to that amount, and USB devices will usually pull less.
And remember where I approximated the "various other things" as using up to 50 W? That includes USB devices.
Speakers usually have their own power source, rather than drawing power from a computer's power supply. So, incidentally, do monitors, routers, and printers. For that matter, anything that needs more than 2.5 W can't get it through a USB port unless it's USB 3.0 only.
There is actually a "Battery Charging Specification" for USB 2.0 that will allow a qualifying device to draw up to 5A at 5V (25W), however the port has to support it, and the device has to properly identify itself to allow the higher power draw, and a port delivering that much power will not allow communication as well (so it's a dedicated charging port). This isn't normal in a computer though - it's usually wall-dongle chargers or car lighter adapters and such that do this - things that pretty much just provide USB power and nothing else.
Normal USB 1.0/2.0 devices are normally limited to 100mA (0.5W) - kyeboards/mice/etc, or special devices can classify themselves as "high power' and draw up to 500mA (2.5W) - typically USB hard drives and such. USB 3.0 does bump that up to 150mA (0.75W) and 750mA (3.75W).
Newer motherboards and USB hosts have some ports called "iPod charging" or "Battery Charging", and require a special driver to be installed to allow it, and those special ports can supply up to 1.5A (7.5W) while also allowing communications - but it requires a special port and special drivers.
It would take a lot of USB devices to need more than 100W of ancillary power.
Just for further information:
A typical platter hard drive requires upwards of 10W (usually only during spin-up, while operating it takes significantly less) - some models can take upwards of 14W during spinup. Most are around 5-7W.
An SSD usually requires around 2W of power. Some take upwards of 4W.
A typical case fan is about 2W (most motherboards only support 2W per fan port, and 4W total across all fans connected on the motherboard). Some high performance fans can be upwards of 10W (really big, typically loud fans).
A sound card takes ... maybe 10W. Most sound cards can be remade into USB devices, and as such can be made to fit into the power profile for a USB device (2.5W) once you strip out a lot of the extraneous circuitry.
So if you have 3 platter drives 2 SSDs 4 case fans 1 Sound card 1 USB mouse 1 USB keyboard 1 USB headset 2 iPods charging (on charging ports)
We're up to ... about 51W, with the bulk of that being in the 2 iPods charging simultaneously on charging ports. Most computers have significantly less than the above miscellaneous equipment.
Ancillary chips on motherboards take a bit of power too: here's a list of common Intel chips: http://www.silentpcreview.com/forums/viewtopic.php?t=35078 If you still have a Northbridge, they cap out under 30W, with most being around 20W. ICH chips are less than 5W. I bet Southbridges are about the same - around 5W, although I can't find any concrete data for many of them.
But you don't always need to add the Northbridge in, a lot of CPU's have done away with it. Basically... only AMD non-APU CPU's still require a Northbridge, and the top-end Northbridge (990FX) is a <20W chip, Fusion and Intel Sandy/Ivy Bridge have integrated NB into the CPU, and the TDP is included in the CPU TDP). The Southbridge and ICH (or external raid controller for an AMD) are... maybe 10W total.
I missed the additional 50 watts you tossed in there, but it doesnt change the total I come up with on eXtreme calc. The reason I said 3-4 watts per USB was to take into account for the pull differences in USB 2.0 & 3.0, and pulling an average of the two. This amounts to a difference of 2 or 3 watts, which is a really petty amount tbh.
The hypothetical 500w sagging to 480w I'm imagining worst case scenarios such as a 2 year old power supply that rarely gets shut down, and add in factors like heat, less-than-perfect line conditioning, capacitor aging, unexpected TDC spikes, RFI, etc building a perfect storm of worst case scenario. Regardless of brand/quality, any power supply subjected to numerous negative factors can sag. My issue is in not knowing how far under-rated is each PSU for its wattage. Without discussing it with their engineers, no one knows. Again, its a matter of 50 watts and I prefer to overshoot by that much rather than ride on the hope that 450 really means 500.
About the 80 Plus Gold/Bronze certs, they have about as much to do with min/max/peak/continuous wattage outputs as the breed of my neighbor's cat, but I'd agree that a gold is a better choice than bronze (of the same wattage & quality) if the price difference between the two is negligible.
We could debate for days over this 50 watts, but I'm just going to agree that we have slightly different methodologies in chosing the right amount of power supply for a system's needs. Mine works out for me, and if you get the same result thats great. I'll consider the $10 difference as buying piece of mind and you can consider it money well saved.
Comments
I left out a monitor, which is a large chunk of the price difference.
Most of the rest is that I picked a much cheaper processor. The processor I picked has 6 cores rather than 4, but each core is slower, so they'll be roughly even in games that scale well to many processor cores, but an FX-6300 will lose by quite a bit to a Core i5-3570K in games that aren't able to put 6 cores to good use.
In many cases, there will be a measurable difference but with frame rates so high that the diffference doesn't matter. If one processor can get you 100 frames per second and another can get you 150, do you really care about that difference? What if, at the graphical settings you want to use, your video card limits you to 70 regardless of the processor, so you don't even see a real-world difference?
There will be a handful of badly-coded games where the Core i5-3570K really does give you better real-world performance than an FX-6300. But from a coding perspective, it's pretty easy to make games scale well to as many processor cores as you want (or at least a lot more than your game actually needs in order to perform well), so it's only a difference for badly-coded games. The only MMORPGs I'm aware of off hand where you're likely to see a difference are EverQuest II and Guild Wars 2.
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I actually picked a better quality motherboard than Recon. They're different processor sockets for different processors, so you can't just swap motherboards without swapping the processor.
We both picked a Radeon HD 7870. I picked a cheaper one. Recon was scared off by a single user review from someone who bought the one I linked and had it not work, so he decided to have you pay $20 more and give up a $15 rebate to get an equivalent card that also has some bad user reviews, but a lot more good user reviews.
Recon picked a power supply with a higher nominal wattage. I picked a power supply that is much higher quality. For the amount of wattage you're likely to pull (probably never over 300 W if you don't overclock), a Rosewill Capstone 450 W will deliver that power much better than a Corsair CX600 V2. Mine will have much better energy effiiciency and voltage regulation and uses higher quality internal components. Pulling 200-300 W under fairly heavy gaming loads isn't enough stress on a high quality 450 W power supply to be problematic. If you have ideas about overclocking everything to the moon and seeing if it fries, then my power supply could be more of a problem.
As for brand name, yes, an average Corsair power supply is better than an average Rosewill power supply. But a low end Corsair power supply certainly isn't better than a high end Rosewill one. (The Corsair CX600 V2 is actually made by Channel Well, while the Rosewill Capstone is made by Super Flower, so neither company actually manufactures their own power supplies.) It's kind of like saying that for Windows, an average Nvidia GPU is faster than an average AMD GPU. (This is actually true, largely because AMD still makes a lot of integrated graphics and Nvidia doesn't.) But that doesn't mean that a low end GeForce GT 520 is faster than a high end Radeon HD 7970; to the contrary, the latter is faster by more than an order of magnitude.
The memory and optical drive that I picked are equivalent to the ones Recon picked. But mine cost $2 less.
Recon picked a faster, smaller hard drive that is also a little more expensive. And a lot noisier. VelociRaptors have been basically obsolete for a few years now because Western Digital wanted to charge enough to buy a VelociRaptor that you could buy an SSD for that price and get something orders of magnitude faster. But at $70, I wouldn't be critical of buying one--though you should be warned that they're noisy.
We picked different cases. I think the case I picked is probably a little higher quality, but that's only a guess.
Recon wants you to waste $10 on aftermarket thermal compound. I say that's completely stupid. AMD's FX processors ship with a much better stock cooler than Intel's processors, so my build gets you much better CPU cooling even without spending $10 on thermal compound.
Recon picked Windows 7 while I picked Windows 8. It's the same price either way, so which you choose is a matter of personal preference.
OK that clears alot of things up.
An thanks for the help. Im looking to get alot of the parts within the month with left over money an picking up the few parts within the next few weeks.. Its a timly process but I wanted to make sure what I was getting.. Nothing is final simply cause I wanna get this right the 1st time if you know what I mean lol. $900 is really pushing It an I wanna make sure I dont buy something Im gonna regret.
Personally on your budget I would go with the AMD build Quiz linked, with the bIgger SSD ( 240G).
I built my brother something very similar and it runs like a champ. If you are willing to up your budget some for an I5 and a z77 motherboard then IMO it would be a bit better computer. But for your needs that AMD build will do everything you want it to do and more while staying in your budget.
You can always save an buy another monitor later, I would not try and include a monitor in an $800 build. Get a decent box, use what you have until you can budget for a better monitor.
My 2cp
Hopefully you have someone who can help or put this together for you?
Prices change, and parts that are a good deal today might not be a good deal a month from now. So don't just wait a month and then buy the parts off of some old list or you're nearly guaranteed to overpay by $50 or $100 or some such.
Maybe their estimates are REALLY far off.. Im not sure. I'm going to dig around for real numbers on wattage draw for these components.
You do realize that the nominal wattage on a power supply is a marketing figure and not an engineering one, don't you? If Rosewill had decided not to be so conservative and called it a 500 W power supply without changing the internals a bit, would that make it magically able to deliver more wattage? A lot of power supply vendors do list inflated wattage ratings, so power supply calculators tend to overestimate how much wattage you actually need because they don't know if you're going to buy some piece of junk that will give off sparks and smoke if you try to pull anything with 100 W of the rated limit.
Can a Corsair CX600 V2 deliver more wattage while staying in spec than a Rosewill Capstone 450 W? Probably. How much more? There's a pretty good chance that the gap is less than 150 W.
A Radeon HD 7870 has a default PowerTune cap of 190 W. An FX-6300 has a TDP of 95 W, which is basically enforced by reducing turbo clock speeds if necessary. Thus, the two big power consumers are capped at a total of 285 W, so even an artificial stress test won't pull more than that. Real games will usually pull far shy of that, especially considering that it is exceedingly rare for a game to push six cores hard, as such a game would probably be unplayable on a dual core processor. So the CPU and video card added together will probably never pull 250 W in real world usage. There are a bunch of other random things that will pull a few watts here and a few watts there, but that probably won't add up to 50 W even.
Thats off. maybe they are trying to oversell a PSU?
I plugged his components into another site and came up with a min 300w psu with a recommended 350w PSU.
http://www.extreme.outervision.com/PSUEngine
Either way a 450w psu for a system at stock settings is more than enough. IMO nothing wrong with getting more than you need. I personally would rather buy a gold / plat certified PSU at lower wattage than a certified/ bronze PSU at a higher wattage.
I personally use the seasonic 550w gold certified, and I overclock my I5 some.
Either way that newegg estimate is off, the site I used was calculating the cpu at 90% TDP to come up with 300w.
I'm not disputing your brands of choice... only the systems wattage requirements. My point is that yes, since ratings are driven by marketing a 500w continuous could actually deliver 540watts max. but it also means that with RFI, heat, aging, etc it could also hit sags and fall to 480w intermittently. There are also wattage needs that you're overlooking. Each USB device thats plugged in is going to bump up the wattage need by about 3-4 watts each, so I estimated 5 devices (15watts) that need figured into tthe draw to allow for things like a keyboard, USB mouse, Headset, Cell or iPod charger & desktop speakers.
My total on a more trusted wattage calculator is showing this to be right at a 450watt draw for the AMD FX-6300 setup you're recommending (calculated with 5 USB devices, having the SSD/7200 setup and with no overclocking of the GPU or CPU). I just think that recommending at mimimum a 500w rated PSU would be a more responsible recommendation and allow a safer ceiling for unanticipated future draw increases such as overclocking the GPU via Catalyst software.
http://www.extreme.outervision.com/PSUEngine
The USB 2.0 specification only specifies power delivery of up to 2.5 W. If you try to pull 3-4 W from a USB 2.0 port, bad things will probably happen. USB 3.0 bumps that up to 4.5 W. But again, that's only up to that amount, and USB devices will usually pull less.
And remember where I approximated the "various other things" as using up to 50 W? That includes USB devices.
Speakers usually have their own power source, rather than drawing power from a computer's power supply. So, incidentally, do monitors, routers, and printers. For that matter, anything that needs more than 2.5 W can't get it through a USB port unless it's USB 3.0 only.
I use more or less the same thumbrule (TDP of CPU/GPU + 100W). That 100W is more than enough to cover USB devices, hard drives, motherboard devices, sound cards, fans, water pumps, and any other ancillary devices you want to include. It would take a lot of fans or hard drives, and a whole lot of USB mice/headsets/keyboards, to require bumping that number up significantly.
If a 500W power supply sags to 480W intermittently , that is a bad power supply. Whatever reason or rationale you want to throw at it, it still boils down to a bad power supply. A good power supply, on the other hand, will deliver 100% of it's rating, even if the wall voltage sags, or it starts to overheat, or starts to age, or whatever - and if it hits a condition where it cannot deliver 100% of it's rating, it should shut down rather than try to fry your electronics (probably due to either an overcurrent limiting device, or thermal protection shutdown). Most good power supplies actually do this - the problem is that most power supplies are not good, and most PC review sites aren't in-depth enough to be able to tell if they can do this or not, because testing for this kind of stuff is difficult and requires some rather sensitive and expensive equipment.
Coincidentally, the Wattage won't sag in your exmaple, it will remain constant because that's dependent on the load. The Voltage will sag, but since the load remains the same, the Current must go up by the same factor (by the electromagnetic definition of a Watt). By a correlating law of physics (Joule's Law), as the current goes up the heat goes up by a power of 2. This is why bad power supplies are so bad, and why voltage ripple, and to a greater extent, voltage brownouts, are such major electronic killers.
There is actually a "Battery Charging Specification" for USB 2.0 that will allow a qualifying device to draw up to 5A at 5V (25W), however the port has to support it, and the device has to properly identify itself to allow the higher power draw, and a port delivering that much power will not allow communication as well (so it's a dedicated charging port). This isn't normal in a computer though - it's usually wall-dongle chargers or car lighter adapters and such that do this - things that pretty much just provide USB power and nothing else.
Normal USB 1.0/2.0 devices are normally limited to 100mA (0.5W) - kyeboards/mice/etc, or special devices can classify themselves as "high power' and draw up to 500mA (2.5W) - typically USB hard drives and such. USB 3.0 does bump that up to 150mA (0.75W) and 750mA (3.75W).
Newer motherboards and USB hosts have some ports called "iPod charging" or "Battery Charging", and require a special driver to be installed to allow it, and those special ports can supply up to 1.5A (7.5W) while also allowing communications - but it requires a special port and special drivers.
It would take a lot of USB devices to need more than 100W of ancillary power.
Just for further information:
A typical platter hard drive requires upwards of 10W (usually only during spin-up, while operating it takes significantly less) - some models can take upwards of 14W during spinup. Most are around 5-7W.
An SSD usually requires around 2W of power. Some take upwards of 4W.
A typical case fan is about 2W (most motherboards only support 2W per fan port, and 4W total across all fans connected on the motherboard). Some high performance fans can be upwards of 10W (really big, typically loud fans).
A sound card takes ... maybe 10W. Most sound cards can be remade into USB devices, and as such can be made to fit into the power profile for a USB device (2.5W) once you strip out a lot of the extraneous circuitry.
So if you have
3 platter drives
2 SSDs
4 case fans
1 Sound card
1 USB mouse
1 USB keyboard
1 USB headset
2 iPods charging (on charging ports)
We're up to ... about 51W, with the bulk of that being in the 2 iPods charging simultaneously on charging ports. Most computers have significantly less than the above miscellaneous equipment.
Ancillary chips on motherboards take a bit of power too: here's a list of common Intel chips:
http://www.silentpcreview.com/forums/viewtopic.php?t=35078
If you still have a Northbridge, they cap out under 30W, with most being around 20W. ICH chips are less than 5W. I bet Southbridges are about the same - around 5W, although I can't find any concrete data for many of them.
But you don't always need to add the Northbridge in, a lot of CPU's have done away with it. Basically... only AMD non-APU CPU's still require a Northbridge, and the top-end Northbridge (990FX) is a <20W chip, Fusion and Intel Sandy/Ivy Bridge have integrated NB into the CPU, and the TDP is included in the CPU TDP). The Southbridge and ICH (or external raid controller for an AMD) are... maybe 10W total.
I missed the additional 50 watts you tossed in there, but it doesnt change the total I come up with on eXtreme calc. The reason I said 3-4 watts per USB was to take into account for the pull differences in USB 2.0 & 3.0, and pulling an average of the two. This amounts to a difference of 2 or 3 watts, which is a really petty amount tbh.
The hypothetical 500w sagging to 480w I'm imagining worst case scenarios such as a 2 year old power supply that rarely gets shut down, and add in factors like heat, less-than-perfect line conditioning, capacitor aging, unexpected TDC spikes, RFI, etc building a perfect storm of worst case scenario. Regardless of brand/quality, any power supply subjected to numerous negative factors can sag. My issue is in not knowing how far under-rated is each PSU for its wattage. Without discussing it with their engineers, no one knows. Again, its a matter of 50 watts and I prefer to overshoot by that much rather than ride on the hope that 450 really means 500.
About the 80 Plus Gold/Bronze certs, they have about as much to do with min/max/peak/continuous wattage outputs as the breed of my neighbor's cat, but I'd agree that a gold is a better choice than bronze (of the same wattage & quality) if the price difference between the two is negligible.
We could debate for days over this 50 watts, but I'm just going to agree that we have slightly different methodologies in chosing the right amount of power supply for a system's needs. Mine works out for me, and if you get the same result thats great. I'll consider the $10 difference as buying piece of mind and you can consider it money well saved.