GPU x16/x16 mode PCIe 2.0 problem

DustSailor · 13 May 2011

So I bought 2 new GPUs SLI, and discovered to my horror that they get very hot because the motherboard (See System Specs) has them touching each other (one of them gets no air at all). So one GPU really heats things up in there.

Sooo now I need another motherboard, and I'm getting poor. I was looking at some Sabertooth: ASUSTeK Computer Inc. - Motherboards- ASUS SABERTOOTH X58 and Rampage_III_Black_Edition: ASUSTeK Computer Inc. - Motherboards- ASUS Rampage III Black Edition

I am basically looking for a cool, stable board that supports as much x16 pcie 2.0 modes as possible, and these both support 2. Also looking for a board that spaces them apart rather than together (Gigabyte didn't think that one through). Are these good boards, or should I keep looking for something else?

Thanks brovs

DustSailor · 13 May 2011

I've taken computers apart and put them back together, but I haven't ever moved the motherboard or CPU, let me know if someones got a link to a clean-up/re-application of thermal compound included in a CPU install.

You guys are the best

Terronium 12 · 13 May 2011

Isn't the Black Edition somewhere north of $540? It'd definitely be cheaper to go with the Sabertooth. EDIT: Hm. After looking at it again, it looks as if the two beige (?) slots are likely 16/16x. If you used one of those and the black slot on the bottom you'd be dealing with 16/8x - which, technically, is a bad thing but considering your cards would likely over saturate even two slots with full 16 lanes none of that wouldn't matter unless you're a benchmarker.

As for TIM removal and re-application, get yourself a couple of these: Remover & Surface Purifier
and when you're about to remove the TIM apply a few dabs of the remover (be sure to cover the entire IHS surface area) and let it set for about 30-60 seconds. Then wipe it off with a cotton ball or an anti-static cloth, and continue to wipe until it's practically gone. Once that's done apply the surface purifier and you can either wipe it off straight away after you're done applying it, or you can let it sit for about 10-15 seconds and then wipe it off - the choice is yours. Basically all the purifier is doing is removing any leftover traces of the TIM or anything else that would interfere with the thermal properties of the TIM and the IHS.

Once you're about to reapply the material do so either straight across or straight down the middle of the IHS. This provides more of an even spread once the material expands and will 9 times out of 10 cover the entire IHS. Don't overdo the application though or you'll end up having to do it all over again.

Visual aide (Heh. I'd forgotten all about the older method; I've been with my Q660 for far too long):

Everlong · 13 May 2011

Don't get the Sabertooth x58 if you're looking for spacing between GPUs. You'll be in the exact same spot. I have that mobo and suffer from the same issue. I'm now in the process of saving up for watercooling.

DustSailor · 13 May 2011

Everlong said:

Don't get the Sabertooth x58 if you're looking for spacing between GPUs. You'll be in the exact same spot. I have that mobo and suffer from the same issue. I'm now in the process of saving up for watercooling.

Yea, probably should have done that. Right now I only have water cooling for my processor. But my card on the bottom, that actually gets air, gets enough and is pretty cool. the card sitting over it gets hot, it went up to 82C in under 5 minutes playing a high graphics game. The other one stayed under 65C, which I hear is okay. I think if they were spaced, both cards would get even lower temps, I'd guess a 60C/60C.

Everlong · 13 May 2011

If they both get adequate cooling, you'd see at max a 10-15C difference in temperatures, which is normal for SLI. I was playing Crysis 2 with my setup and the top card reached 100C

I managed to cut a hole in the back of the top card to allow airflow in through the back, which helped a bit, but it still gets quite toasty in there.

DustSailor · 13 May 2011

Now with a board that supports x16/x16 and x16/x8/x8 pcie 2.0 modes: with 3 pcie 2.0s, if I had my two SLI graphics cards in the 2 sli locations and an extra card for phisics in the third, would that grant a x16/x16 mode for the sli cards and maybe x4 for the phisics, or would it go to the x16/x8/x8 modes? I'm not completely familiar about what those modes are or what they mean, but would it be worth it, or should i get rid of a card and keep the 2 sli in order to keep the 2 x16 modes?

let me know if i need to rephrase for clarity

Terronium 12 · 14 May 2011

DustSailor said:

Now with a board that supports x16/x16 and x16/x8/x8 pcie 2.0 modes: with 3 pcie 2.0s, if I had my two SLI graphics cards in the 2 sli locations and an extra card for phisics in the third, would that grant a x16/x16 mode for the sli cards and maybe x4 for the phisics, or would it go to the x16/x8/x8 modes? I'm not completely familiar about what those modes are or what they mean, but would it be worth it, or should i get rid of a card and keep the 2 sli in order to keep the 2 x16 modes?

let me know if i need to rephrase for clarity

I've never messed around with SLI so I can't really comment with certainty, but unless you can specify which GPU does what type of calculation...it's really left up to the games engine and programming. If it doesn't support PhysX then you're basically out of luck. And once again, don't place too high of an importance on how many lanes are going to be available to your setup, because unless you benchmark like a mad man you absolutely are not going to notice any difference in frame rate or overall performance. I can't remember for certain right now but I don't think a 16x slot can, in any situation, limit the bandwidth to that of a 4x slot.

I'd say you're better off sticking with just a two card setup.

Everlong · 16 May 2011

DustSailor said:

Now with a board that supports x16/x16 and x16/x8/x8 pcie 2.0 modes: with 3 pcie 2.0s, if I had my two SLI graphics cards in the 2 sli locations and an extra card for phisics in the third, would that grant a x16/x16 mode for the sli cards and maybe x4 for the phisics, or would it go to the x16/x8/x8 modes? I'm not completely familiar about what those modes are or what they mean, but would it be worth it, or should i get rid of a card and keep the 2 sli in order to keep the 2 x16 modes?

let me know if i need to rephrase for clarity

Depends on the motherboard chipset. The Sabertooth x58 uses an x16/x16/x4 setup if the third slot is occupied. Or if the PCI-E x1 slot next to it is occupied, then the third PCI-E slot becomes an x1 slot as well. x4 would be enough for Physx though.

It might be different for the motherboard you have now though. You'd have to have a look in the manual.

DustSailor · 16 May 2011

I just bought the asus rampage III formula mb, and decided to leave out the physx 460 card and just keep SLI. Which means I need to sell the card to get rid of it lol. I hate selling crap

I had no idea or even thought about the effect an occupied pci-e x1 slot would have. Lucky I'm using a USB adapter now though. Wish computers weren't so complicated. But its fun to learn them all the same.