I'm looking to build a new gaming PC that will last a while. I want to use a PCI-E x8 SSD + GTX 780 SLI in this build.

Now i'm looking around on the web to see what i need to support this in terms of motherboard and CPU.

My first setup was:

  • CPU - i7-5820K (Support PCIe 3.0, with 28 lanes)
  • Motherboard - ASRock X99 Extreme4 (Support for 36 lanes, with a 28 lane cpu the slots will be 16x-8x-4x)

So here i would think that my setup with a pci-e x8 ssd won't work cause the third slot is only pci-e x4.

second setup:

  • CPU - i7-5930K (Support PCIe 3.0, with 40 lanes)
  • Motherboard - ASRock X99 Extreme6 (Support for 40 lanes, with a 40 lane cpu the slots will be 16x-16x-8x)

here i would think this is ok with the pci-e x8 ssd. but it also much more expensive. and i read different things about how the the pci-e lanes work.

so please can someone help me out here and tell me how this pci-e lane stuff really works and if im right in my setups.

-EDIT- Thanks for all the comments guys, really helped me understand how things work a bit. and i think i have made up my mind in terms of what to buy for now. thanks!

  • It would work it just would be limited to x4 speeds. It sounds like you want the better hardware. – Ramhound May 11 '15 at 14:38
  • With a PCIe SSD, you appear to be placing the emphasis on disk speed rather than graphics power. For a gaming PC, this is not the usual way to go. However, even the new Intel 750 SSD "only" uses four PCIe lanes - what is the eight-lane PCIe device that you are considering? – Andrew Morton May 11 '15 at 15:00
  • Indeed the emphasis on speed for a gaming pc is somewhat strange but i want to see what this baby can do :) Mushkin Scorpion Deluxe, 240 GB PCIe SSD – Bram ten Cate May 11 '15 at 17:37
  • By the way: Instead of buying a needlessly fast PCIe SSD with only 240 GiB, get a 500 GiB or even 1 TiB SATA SSD. SSDs main improvement over HDDs is fast random access. You also get this with regular SATA SSDs. – Daniel B May 11 '15 at 18:10
  • Please note that the Mushkin drive uses PCIe 2.0, if that makes any difference. – Andrew Morton May 11 '15 at 18:50

PCI-E slots can have 1, 4, 8 or 16 lanes. A CPU supports a specific number of lanes.

The term "lane" is used because each lane is not shared with any other device, and this is why it's faster than standard PCI. I/O bandwidth on the older PCI standard was shared amongst all devices on the bus. A device like a PCI graphics adapter or heavily utilized Ethernet adapter could saturate the bus, leading to contention and slowdown. One of the reasons AGP was developed was to basically put the graphics card on its own 1-device bus.

Obviously, more lanes = more speed. Graphics cards are typically 16x.

A card can be put in a slot with less lanes than it needs (if motherboard components don't get in the way), but it will operate slower. A card can be put in a slot with more lanes than it needs, but you lose the extra lanes. It won't make the device any faster.

Some chipsets do weird things with PCI-E lanes. I've heard of some motherboards (will update if I find the info) depending on the type of cards you have in other slots, a 16x slot may become an 8x slot.

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  • thanks for this information.with every post i geet a better understanding of how it works :) for the ssd in mind a 4x slot seems ok, i lose a bit of read speed but thats ok vs the costs. – Bram ten Cate May 11 '15 at 17:48
  • 1
    "More lanes = more speed" - also: higher PCIe version = more speed per lane. – Andrew Morton May 15 '15 at 20:55

The lanes basically carry bandwidth in one direction or both (dual directional). The performance for gaming between 8x and 16x is negotiable with today’s current graphics cards, maybe a few FPS gain in certain situations.

As for your set-up the first one should be fine by my calculations, the 16x and 8x slots will have no problems running the cards.

This leaves you with the 4x for your SSD which gives you a theoretical speed of 2000MB/s of bandwidth, now from my understanding this is about the limit of most current PCI-e SSD cards so I think you might just get away with it in terms of performance.

You will have to think about future proofing though, what if you want a faster SSD in the future then having the extra 8x will be important.

  • hi!, thanks for this amazing information. i was thinking about getting a "Mushkin Scorpion Deluxe, 240 GB PCIe SSD" read speeds are 2150MB/s and write speeds are 1950MB/s. so that would be good for 4x, might lose some read speed. but indeed for future proofing the second setup might be better. – Bram ten Cate May 11 '15 at 17:43
  • something to consider is the MSI X99S its in the same price range as your first choice but will run 8x 8x 8x which is enough for all the cards but you may loose some future proofing in the fact IF graphics cards start reaching a point where they can take advantage of 16x you would need to start looking at a new board – twigg May 11 '15 at 20:17

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