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Question: Building a Computer- PSU
I am upgrading my PC and am just wondering if my current PSU is sufficient. I have a 700W or 750W (dont remember which, not at it atm). I am upgrading to the following:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130508
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128358
and 2: http://www.newegg.com/Product/Product.aspx?Item=N82E16820227298
In addition to this I have a Q6600 Intel 2.4GHz Quad processor
2 DVD drives
250GB HDD
and my pc has 2 fans as well.
So is a 700W or 750W (i can update this when i get home to let you all know which it is if that effects the answer) sufficient to power this computer? How can one tell what is a good Wattage to power a computer so I dont got to ask next time 
?
Comments
Yes, it is more overkill than not sufficient, you will not have any problem.
The only good psu calculator: http://web.aanet.com.au/SnooP/psucalc.php
Alright, thanks for the help.
If you're buying a high end video card, you may wish to wait a day. ATI's Radeon HD 5870 and 5850 are strongly rumored to release tomorrow.
Claimed specs have the Radeon HD 5870 giving performance comparable to the GeForce GTX 295, with added DirectX 11 compatibility, much lower power usage, a considerably lower price tag, no need for Crossfire/SLI with only a single GPU, and various other goodies. Independent reviews should be all over the Internet shortly (possibly as soon as an hour from now), to tell us whether AMD is exaggerating performance or the cards are as good as advertised.
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As for whether a 700 W power supply will be enough, it depends a lot on what 700 W power supply you have. If you have a nice one that can reliably deliver 700 W continuously under real world conditions (i.e., mostly on the +12V rail and at the high temperatures that exist in a computer case), a 700 W power supply will be overkill for your system unless you've heavily overclocked the processor--and even then, it would still be sufficient.
If you have a 700 W power supply that is rated at only 500 W on the +12V rails, rated as peak power not continuous, and rated for power delivery at 25 C rather than the much higher temperatures inside a computer case, then trying to stick a GTX 295 in there could be dicey. If you could find the brand of the power supply, that would tell a lot.
The GTX 295 have a reccomended 680W so it should work. You might get some problem with more than 2 harddrives however if you have the 700W.
As for the specs on the new ATI cards you will have to check their homepage.
I run a 295 myself, great card.
Recommendations are rubbish, the system would work just fine with a modern 500 watt psu.
Power supply ratings vary so much from one manufacturer to the next that they have to estimate on the high side for official recommendations. Some 500 W power supplies can safely deliver 600 W, while others will explode if you try to continuously draw 400 W from them under real-world conditions.
Newegg has a Power Supply calculator that you may find helpful, and you can probably find similar tools on other websites. I would add at least another 100W or 200W to whatever the calculator gives you to be on the safe side. If you have one HDD, you're in that zone. If you have two HDD, you're probably still OK but don't add any more.
The biggest hit to power is, not surprisingly, the addition of duplicate components like running 2 video cards and extra hard drives. If you ever decided to add a second video card, you'll probably need to go up to 800W or 900W.
When you are building a PC, the PSU is not an area to skimp out and go for the cheapest brand. A cheap PSU can do bad things to your PC.
http://educations.newegg.com/tool/psucalc/index.html
You will never ever need 800 watt psu unless you are going to do stuff like quad sli 295 or other as crazy.
I still recommend only using the calculator I posted some messages ago, the only realistic one I've seen.