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PCI-E lanes and limits
I am looking at doing a new build, and I am looking for some good insight into what would yield the best results.
I will be going with a high end motherboard and I will be going with a GTX1080 and I will be putting in 32GB of the appropriate memory. I will have a 512GB OS drive, and 2 1TB gaming drives. Herein lies the question;
Looking into the CPU's there are limitations that I need more understanding with. The i7-6700K has a maximum support 16 PCI-E lanes and the motherboard I was looking at (MSI Z170A GAMING M9) supports 3 PCI-E x16. Now I may want to look at running a second card later, but for now it's just the single 1080. I am looking at the prospect of using an NvMe PCI-E for one of the solid states but will that take away from the capabilities of the videocard because the limited PCI-E lanes provided by the CPU. And is a second card a complete waste money because of the same limitation?
Thanks in advance.
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I get banned in the forums for games I love, so lets see if I do better in the forums for games I hate.
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I offer this post as some additional insight into your question http://superuser.com/questions/1020268/does-m-2-ssd-card-mess-with-pci-express
It is hard to determine where actual bottlenecks will occur in future gaming, transfer rate vs lane width for stacking etc so the choice isn't very clear cut. Will transfer rate on your storage start hitting the ceiling enough to affect performance(it doesn't now) or will graphic textures require 10GB cached to reduce stuttering(it doesn't now)
2+ GPU's arent usually needed even for 4k gaming(assuming you have at least a 6GB vid card), but VR could change that and M2's are nice and super fast but sata 3.0 is more than enough for most any game as they don't tend to load and unload that much data into ram that often(again VR textures could change this)
Edit: I should add with fairly basic water cooling the 5930k run at 4.2G at 40C. I think it runs at that temp with it at 3.5G too so it seems to make no difference. It has a much lower default clock speed but it stays at the same temps at about the same speed as my wife's 4790k. I am not a big overclocker as it usually provides very little benefit but you have to turn up the 5930k a bit or it just seems silly.
Several years ago, I saw an experiment where they tried using x1 bandwidth instead of x16 for the video card in various games. Results varied from no meaningful performance difference to cutting performance in half.
The answer to the question you intended to ask but couldn't formulate is, don't buy a GTX 1080 now with the intention of adding another one for SLI later. SLI is very hit and miss, and relies heavily upon game-specific driver optimizations. Those optimizations tend to only get done for a relative handful of the most high profile games, and stop when a new architecture comes out and is the focus of new driver optimizations rather than older cards.
If you expect that a GTX 1080 won't be fast enough in the near future, then either get a Pascal-based Titan X, or wait for a cut down version of it or to see what AMD Vega offers. If you expect to want an upgrade over your GTX 1080 in a few years, the sensible thing to do then will be to pull out the GTX 1080 and replace it by a single Volta or Navi or whatever is available then card.
Thank you both, but I think I'm more confused now then I was before! lol
Does the motherboard offering more PCI-E lanes than the CPU is spec'd for, create a bottleneck once the limitation has been exceeded?
All of my posts are either intelligent, thought provoking, funny, satirical, sarcastic or intentionally disrespectful. Take your pick.
I get banned in the forums for games I love, so lets see if I do better in the forums for games I hate.
I enjoy the serenity of not caring what your opinion is.
I don't hate much, but I hate Apple© with a passion. If Steve Jobs was alive, I would punch him in the face.
Using all of the PCI Express lanes above doesn't just mean having something plugged into them. It means actively using all of the bandwidth. If you have various SATA, USB, and PCI Express devices using a little bit of bandwidth, but far less than the bandwidth connecting the chipset to the CPU, the chipset can assemble that how you'd hope and everything works fine.
What does become an issue is if you plug in a second video card and instead of two PCI Express 3.0 x16 connections, the motherboard has to split the bandwidth between two video cards for two x8 connections. That's usually not a huge problem for games, but it is a meaningful concern.
These z170 boards usually have 20 lanes, 16 straight to the cpu and any more to the southbridge. The extra PCI lanes are controlled my the south bridge, well PCH as it is called these days. Yes it is sort of a router that specifies traffic to the cpu but that will happen anyway with any HDD, SSD or otherwise. So an m.2 drive even with it's own dedicated slot will disable use of some sata ports and they will all share the same highway. Basically the gpu with get a direct lane to the cpu regardless and the only time you will be impacted by this when gaming is you were some reason transferring a ton of files from one drive to another.
(read way more than just offloading data from a drive into system cache graphics or otherwise because thats such a small amount you won't notice it) I can't imagine where this situation would occur frequently unless you were hosting a game server on it and doing back ups to another drive while playing and downloading... you get the idea.
Your problem is you want a board that will run PCI-E 3.0 in sli at 8x/8x and still want a dedicated lane for a single M2 drive that will run at 4x. Thats a feature of the skylake boards but varies board to board. The board you linked says it will indeed run 8x8x4x. This seems to be an error and I am sure they mean their m2 slot can run at 4x seperately because it is impossible, but crappy advertising for mobo's is all the rage now.
The board scares me for other reasons though and thats its integration of wifi bandwidth piggybacking on your ethernet connection. It seems like they try and route traffic to both adapters and that seems like a clusterf*** for minimal gain. Ethernet only is fine lol. Im pretty sure this can be disabled. Also I am not thrilled about their controller. I will look around at boards for one thats a bit cheaper and probably has better architecture.
I will also parrot what quiz said and that you really won't notice the difference even if you loaded up a single gpu and it got stuck at 8x because you had a lot of M2 drives and stuff stealing you pci-e lanes.
For almost all gamers a single 1080 and a 6700k and a single sata 3 SSD will do them just fine for a long, long time. That includes streaming while playing some of the newest titles if thats your thing. If you really wanted to SLI for sure and envisioned running one or multiple m.2 or the newer NVMe drives I would go for a more robust chipset built around a 5930k or something similar like I did which actually have lanes available that won't steal from the others as much.
"The real issue with M.2 is that on Intel systems it's generally implemented behind the PCH (Platform Controller Hub), which features only Gen 2 PCIe. That's because the PCH lies behind the DMI (Direct Media Interface) which is capped at 2GBps. You can see the problem" The future of storage drives, NVMe
The second question: Yes, but not for the reasons your giving here.
NVMe is the "new" specification for the hard drive interface and you've been able to buy NVMe storage since 2012. Both Linux and Windows added support for it in 2012. For those unfamiliar you plugged the storage into a PCI-e slot. It was very expensive. So people went with SSDs, maybe a quarter of the price for two or three times the capacity.
M.2 is the "new" form factor for storage. The driving force being was mobile. Motherboards started to introduce M.2 slots after the standard was agreed in 2014. Most new ones will now have an M.2 slot. The storage lies flat on the motherboard. No case and no cables. If anyone has opened up an SSD recently they will have seen they were mostly empty! The form factor is obviously good for mobile devices.
Interface innovation + Form factor innovation = best of both worlds and cheaper to manufacture (no case, less "assembly", no cables, huge volume production - PCs, laptops, tablets).
Hence what is available today is M.2 NVMe. Affordable NVMe an M.2 form factor.
As TheFunky1 said: it is the future.
Thanks again.
The build is going to be focused mainly on flight sim and will require 1TB dedicated to game files. Dual M.2 drives and a single NvMe PCI-E is what I am thinking, but I need to decide if that is better than SATA SSD's for the price. If they were going to bottleneck the capabilities of the video, I would have been concerned.
All of my posts are either intelligent, thought provoking, funny, satirical, sarcastic or intentionally disrespectful. Take your pick.
I get banned in the forums for games I love, so lets see if I do better in the forums for games I hate.
I enjoy the serenity of not caring what your opinion is.
I don't hate much, but I hate Apple© with a passion. If Steve Jobs was alive, I would punch him in the face.