No Full Support for 3-way SLI by X58 motherboards?

[KiDo]

I noticed something puzzling about the new X58 Motherboards which appears to me that they don't have full support for 3-way SLI.

In the "Expansion Slots" section of the specifications of ASUS P6T Deluxe V2 , it says

"3 x PCIe 2.0 x16 (at x16/x16/x1 or x16/x8/x8 mode)"

But in the same section of ASUS Striker II, it says

"2 x PCIe 2.0 x16 ,support NVIDIA® SLI™ technology, at full x16, x16 speed(blue); 1 x PCIe x16 ,at x16 speed(middle)"

followed by "Scalable Link Interface" section saying that it

"Support NVIDIA 3-way SLI graphics cards (triple at x16 mode) "

Considering this difference between the two motherboards, which both are among top of their classes, can I make the conclusion that 790i Ultra (790i & 780i also) motherboards support 3-way SLI better than X58 motherboards?

Asus Rampage II Gene specification: http://usa.asus.com/products.aspx?l1=3& ... odelmenu=2
Asus Strike II specification: http://usa.asus.com/products.aspx?l1=3& ... odelmenu=2
Nvidia motherboards specification: http://www.nvidia.com/docs/IO/35382/LC_ ... _Mar08.pdf

[InspectahACE]

No. the 790 doesn't really support tri-sli any better than the x58..you wouldn't notice a difference between the 2 really honeslty(especially if you got 3 gpus installed already)..other than what cpu they use..by the way, the Asus Gene board only has 2 pci-e slots the Rampage II Extreme does though. the main thing why you see that is, nvidia's chipsets provide more lanes than what they licensed the x58 for(if i read right)..regardless, you wouldn't see a difference between the 2 boards, just what cpu you would use on them

[KiDo]

Thanks for your reply ACE

I later noticed the point you mentioned that Asus Gene only has two PCIe 2.0 slots so I checked Asus P6T which has three PCIe 2.0 slots and edited the original post.

After looking at the specification of other X58 motherboards that have three PCIe 2.0 x16 slots, I found that non of them support three VGA cards at "triple x16 mode", but at either X16,x16,x1 or x16,x8,x8 because the third slot shares bandwidth with the second one.

I also found something might be the downside about 780i (and up) motherboards that they, instead of having three PCIe 2.0 x16 slots, only offer two PCIe 2.0 x16 slots and a third PCIe 1.0 x16.

But my problem still remains here. By definition, PCIe 2.0 has double the bandwidth of 1.0, that is 2x16=32. But this is the case when you use only one of those PCIe 2.0 slots. If you use two PCIe 2.0, they will work at x16 the same time, which is the speed of PCIe 1.0. As a result 780i (and up) motherboards having an extra PCIe 1.0 x16 slot could support 3-way SLI better than X58 motherboards having one PCIe 2.0 slot with full x16 bandwidth and two PCIe 2.0 slots with shared bandwidth of x16.

It will be great if Legit reviews can have a comparison review on this issue

[InspectahACE]

no problem. I wouldnt object to a review myself, but the difference would be small i would think.. you would get maybe 5 fps more in a game(maybe 10 in certain games) but that's about it....i still remember when SLI first arrived it was at 8x,8x..and when they got to the full 16x on both lanes, the difference wasn't too much at all but there was one..it would probably be the same here with the 3 slots..The Asus WS Revolution(X58) board has full 16x on 3 slots..but it also has 6 pci-e slots total.no other kind of slot..I doubt you could run 6 in SLI due to lane restrictions (can't run 16x on all 6) plus if you ran 3 280's(or any dual slot cards) the other slots would be covered..but that's all i know of that board..


Welcome to the Forums by the way

[Bio-Hazard]

Not all X58 boards are created equally............................

As for the standard P6T that you referred to it does have 3 x16 slots, but in triple use, it provides 16 x 16 x 4, a bit different than some.

[InspectahACE]

Not all X58 boards are created equally............................

you saying your board's bigger than mine? lol j/k.. yea..it would've been cool if they made them equal but i also don't see nvidia doing that since they could make money with their own chipset doing full speed...I forget the exact word but i think it was called Capitalism(had to google it so i might be wrong lol)...gotta love it