SLI problems on an ASUS Rampage II Extreme

[StormClaw]

Gentlemen, I'm running two 285 GTX in SLI on an ASUS Rampage II Exreme

Referrence layout design here: http://nx.i4memory.com/x58manuals/rampage2extreme/rampage2extreme_motherboard_layout.png

Cards are placed in PCIEX16_1 and PCIEX16_3

However, one card is running at 16x width and the second one is running at 8x width.

What gives? I was under the impression all 3 PCIEX16 slots supported 16x.

 

[bubblethumper]

I have the same motherboard and Slot 3 is only capable of 8x (at the highest). The two blue slots are the only ones that are capable of full 16X. Here is the page from the manual:

 

[StormClaw]

well, crap

 

[xp3nd4bl3]

well, crap

Is there something wrong with operating your 285 at PCIe 2.0 x8? My GTX 480 has no problems with it.

 

[StormClaw]

My GTX 480 has no problems with it.

you know this, how?

 

[xp3nd4bl3]

you know this, how?

Awesome SLI scaling and full GPU load?

This is something that's been tested and retested and discussed like hell over the last couple years. pcie 2.0 x8 is plenty of bandwidth for todays cards.

 

[StormClaw]

Awesome SLI scaling and full GPU load?

im not talking about not having problems with it, i'm talking performance

how do you know your cards wouldn't perform better running x16/x16 ?

 

[xp3nd4bl3]

im not talking about not having problems with it, i'm talking performance

how do you know your cards wouldn't perform better running x16/x16 ?

Because I've asked myself this question every new generation of GPU. I tested it on my 5870's, I tested it on my GTX 295's, I tested it on my GTX 285's, I tested it on my GTX 280's.

PCIe 2.0 at x8 is plenty.

http://www.techpowerup.com/reviews/NVIDIA/GTX_480_PCI-Express_Scaling

 

[Matrices]

There's nothing to cry about here. It's a meaningless loss, maybe 2 to 5%, going from 16x to 8x. Even 4x is only a 10% loss.

 

[dook43]

im not talking about not having problems with it, i'm talking performance

how do you know your cards wouldn't perform better running x16/x16 ?

test it.... that is unless you overheat in the adjacent slots

What cases actually support 2 slot cards in PCIE_3 on that board anyway? My ABS Black Pearl doesn't.