3+ GPUs with Skylake?

[Henry]

Sup LTT forums,

I want to build a dedicated folding@home PC, with 3 graphics cards running independent of each other. However, since Skylake only has 16 pci express lanes, and since 95% of Skylake motherboards don't support SLI (which leads me to question whether running 3 graphics cards independently would even work), would the 3 graphics cards run in 8x 4x 4x, or would only 2 graphics cards work, and the 3rd one not work at all?

EDIT: Ik now that SLI requires, 8x on all cards no matter if it's PCIe 3.0, 2.0, etc, which is why 3 way SLI wouldn't work for obviously reasons. Still haven't figured out if the 3 graphics cards would work independently in 8x 4x 4x

[S7117]

6 minutes ago, Henry said:

Sup LTT forums,

I am thinking about a future 3x GPU PC dedicated to folding@home (so the GPUs won't be in SLI, just running independently). However, most motherboards, including this one that I might get: http://www.newegg.com/Product/Product.aspx?item=N82E16813132691, don't support 3 way SLI, because Skylake chips only have 16 pcie lanes. 

Since I won't be running the cards in SLI, would I be able to run 3 graphics cards independently on a typical Skylake motherboard? I'm assuming 1 card would run in 8x mode and the others run in 4x mode?

Skylake has 16 PCIe lanes and I believe when I spoke with intel they told me that the chipset bumps it up to 20. You probably shouldn't do a 3-way SLI though. What GPU's would you use? I would go for an X99 build if you are going to do a 3-way SLI. More PCIe lanes and motherboards that have support for them.

At most I believe skylake would try and x8 x8 x4(chipset) or a x4 x4 x4 configuration.

[awesomeness10120]

The only way you can do that is through a motherboard with a PLX chip, such as a Z170 WS.

[Henry]

13 minutes ago, S7117 said:

Skylake has 16 PCIe lanes and I believe when I spoke with intel they told me that the chipset bumps it up to 20. You probably shouldn't do a 3-way SLI though. What GPU's would you use? I would go for an X99 build if you are going to do a 3-way SLI. More PCIe lanes and motherboards that have support for them.

At most I believe skylake would try and x8 x8 x4(chipset) or a x4 x4 x4 configuration.

So...would 3x GPUs actually work, if ran independently? Like I said, it won't be in SLI, but I'm not sure why SLI/no SLI makes a difference.

I have no idea what GPUs, maybe 1070s or 1080s. Depends on whether or not I have the money.

[Henry]

15 minutes ago, awesomeness10120 said:

The only way you can do that is through a motherboard with a PLX chip, such as a Z170 WS.

God damn it Intel, trying to take more money from me... So if I put in a 3rd GPU, I'm assuming it would flat out not work at all?

[SnowyMus]

6 minutes ago, Henry said:

God damn it Intel, trying to take more money from me... So if I put in a 3rd GPU, I'm assuming it would flat out not work at all?

If you check with ARK for the 6700K, the PCIe configurations you can get are 1x16, 2x8, or 1x8 + 2x4. Lots of ATX motherboards have three 16x slots which are typically for graphics cards and aren't routed through the chipset. Basically, it'll work with one card at 8x and two at 4x.

[2FA]

5 minutes ago, Henry said:

So...would 3x GPUs actually work, if ran independently? Like I said, it won't be in SLI, but I'm not sure why SLI/no SLI makes a difference.

I have no idea what GPUs, maybe 1070s or 1080s. Depends on whether or not I have the money.

You don't run GPUs for compute in SLI, you run them independently. You don't really need to worry about a slot being less than 8x.

[S7117]

5 minutes ago, Henry said:

So...would 3x GPUs actually work, if ran independently? Like I said, it won't be in SLI, but I'm not sure why SLI/no SLI makes a difference.

I have no idea what GPUs, maybe 1070s or 1080s. Depends on whether or not I have the money.

Ok... Yeah so Nvidia doesnt support more than 2-way SLI anymore. Plus I just dont see the need for that many on a skylake build... I wouldn't even recommend it on X99. Its just too much money and not really worth it in my mind. It probably wouldnt even work or work well on skylake period

[Henry]

3 minutes ago, DeadEyePsycho said:

You don't run GPUs for compute in SLI, you run them independently. You don't really need to worry about a slot being less than 8x.

Yes I realize I run them independently, I mentioned that in the original post.

So it would work..right? 

[Henry]

3 minutes ago, S7117 said:

Ok... Yeah so Nvidia doesnt support more than 2-way SLI anymore. Plus I just dont see the need for that many on a skylake build... I wouldn't even recommend it on X99. Its just too much money and not really worth it in my mind. It probably wouldnt even work or work well on skylake period

Please read the original post.

[SnowyMus]

6 minutes ago, Henry said:

Yes I realize I run them independently, I mentioned that in the original post.

So it would work..right? 

It should work just fine. Sure, two of the cards will have to run at 4x mode with Skylake, but that won't have any noticeable effect (if any) on performance. PCIe 3.0 is really fast, already.

[S7117]

2 minutes ago, Henry said:

Please read the original post.

I mean I guess they would work in x8 x4 x4 but at that point you are wasting performance on two of them. x8 does not lose any speed really but x4 does.

I would not do it but its your money.

[Henry]

3 minutes ago, Kavawuvi said:

It should work just fine. Sure, two of the cards will have to run at 4x mode, but that won't have any noticeable effect on performance. PCIe 3.0 is really fast, already.

Why would running it independently work, but running it in SLI not work? 

[S7117]

1 minute ago, Henry said:

Why would running it independently work, but running it in SLI not work? 

In SLI it may work with an x8 x8 in SLI and x4 from the chipset but I would talk to Intel and your MB manufacturer. That may be the best thing to do.

 

[SnowyMus]

6 minutes ago, Henry said:

Why would running it independently work, but running it in SLI not work? 

The reason for this is because SLI has a requirement that each card run at 8x or better. It's set by NVIDIA rather than any sort of performance ceiling, so there's really no way around it.

[Henry]

2 minutes ago, S7117 said:

In SLI it may work with an x8 x8 in SLI and x4 from the chipset but I would talk to Intel and your MB manufacturer. That may be the best thing to do.

 

I guess I'll do that. Frickin Intel, only 16 pci express lanes..

[S7117]

1 minute ago, Henry said:

I guess I'll do that. Frickin Intel, only 16 pci express lanes..

Dude why do you need 3?????

[Henry]

2 minutes ago, Kavawuvi said:

The reason for this is because SLI has a requirement that each card run at 8x or better. It's set by NVIDIA rather than any sort of performance ceiling, so there's really no way around it.

ohhhhh, I see. I never knew that. Ty for that info

[Henry]

2 minutes ago, S7117 said:

Dude why do you need 3?????

I already said in the original post. Folding@Home.

[S7117]

4 minutes ago, Henry said:

I already said in the original post. Folding@Home.

In that case i would say you should go for X99 or find a group with some HPC clusters. 

 

Sorry did not see that and did not know what that was. Just looked it up.

[SnowyMus]

15 minutes ago, Henry said:

I guess I'll do that. Frickin Intel, only 16 pci express lanes..

Intel has pretty much always done this. The only way to get more than 16 lanes directly to the CPU is to get a more expensive Xeon CPU or a CPU from Intel's enthusiast architectures (Haswell-E, Broadwell-E, etc.) which could run you up a pretty high bill. You could also use the 20 chipset lanes, but the bandwidth between the chipset and the CPU is limited to 4 lanes, and the chipset needs those for other things as well.

 

13 minutes ago, Henry said:

I already said in the original post. Folding@Home.

F@H isn't compatible with SLI or CF, so the 16 lane limit shouldn't be an issue.

[FRN]

1 hour ago, Henry said:

Sup LTT forums,

I want to build a dedicated folding@home PC, with 3 graphics cards running independent of each other. However, since Skylake only has 16 pci express lanes, and since 95% of Skylake motherboards don't support SLI (which leads me to question whether running 3 graphics cards independently would even work), would the 3 graphics cards run in 8x 4x 4x, or would only 2 graphics cards work, and the 3rd one not work at all?

EDIT: Ik now that SLI requires, 8x on all cards no matter if it's PCIe 3.0, 2.0, etc, which is why 3 way SLI wouldn't work for obviously reasons. Still haven't figured out if the 3 graphics cards would work independently in 8x 4x 4x

Check out Luke's last video.

 

 

 

 

 

[2FA]

8 hours ago, FRN said:

Check out Luke's last video

That isn't even relevant to the topic being discussed here.