I have been reading about of few of the mobo's that support 3 or 4 16x pci express sli/crossfire and can't help but wonder....How many lanes does a modern high end gpu need? The fastest cards are 2 gpu cards...be they ATI or Nvidia....when they are in a 16x slot doesn't each gpu only get 8 lanes? Is this part of why you always lose something in scaling from 2 single core cards > 1 dual gpu card? But still...it seams like a high end card doesn't really need all 16 lanes...what say you?
![[H]ard|Forum](/styles/hardforum/xenforo/logo_dark.png){kind=logo}
Navigation
Install the app
How to install the app on iOS
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
More options
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Would't and 2 core gpu only get 8 lanes/gpu?
- Thread starter schoenda
- Start date
jeremyshaw
[H]F Junkie
- Joined
- Aug 26, 2009
- Messages
- 12,511
They are linked internally. either by a PCIe bridge, or a direct SLI/CF link.
PlatinumPC
Limp Gawd
- Joined
- Aug 17, 2008
- Messages
- 315
no they don't. I am running 1 @ 16x and other at x4..and have well above the normal performance. If there was any performance loss it would be only a few percent.
Like microstutter, there has been alot of fear mongering about this whole PCI-E lane business.
At the end of the day, it's barely worth consideration from what I've experienced.
and comming from a GTX295 I can say that I've had a rather huge performance boost due to the increased clocks and lower temps.
Like microstutter, there has been alot of fear mongering about this whole PCI-E lane business.
At the end of the day, it's barely worth consideration from what I've experienced.
and comming from a GTX295 I can say that I've had a rather huge performance boost due to the increased clocks and lower temps.
lollerskater69
[H]ard|Gawd
- Joined
- Jan 3, 2009
- Messages
- 1,231
All the benchmarks I have been reading show that generally x4 is the bottom of the barrel in terms of taking a "small" yet managable loss with high end cards. x8 and x16 shows no loss which is great because that is what p35,p45,790gx, and p55 offers.
very few games need or make use of that bandwidth after a point (like said above 4X pcie 2.0) so there really isn't any reason to worry. out side of MSFSX I can't even thing of a game that takes a significant hit by dropping to 8X pci-e 2.0
In this PCI-E scaling test:
http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/1.html
the fastest single-GPU card (the 5870) did not show significant performance reduction until you got down to a x1 PCI-E 2.0 slot. The only game out of about 20 that showed any significant performance reduction in a x8 PCI-E 2.0 slot was S.T.A.L.K.E.R. Clear Sky, and that only at 2560x1600.
Just be aware that those tests only tested one single-GPU card. I would expect Crossfire/SLI setups or multiple-GPU cards to return different results.
http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/1.html
the fastest single-GPU card (the 5870) did not show significant performance reduction until you got down to a x1 PCI-E 2.0 slot. The only game out of about 20 that showed any significant performance reduction in a x8 PCI-E 2.0 slot was S.T.A.L.K.E.R. Clear Sky, and that only at 2560x1600.
Just be aware that those tests only tested one single-GPU card. I would expect Crossfire/SLI setups or multiple-GPU cards to return different results.
As always, thanks guys. All the new Ubermobo's seem to have there problems...I think I won't worry about it...I will likely go p6t vanilla. Sounds like no worries even up to tri or quad setup...now hmmm, quad cards with physx...never mind... I assume 1x is plenty for physx..maybe 4 at the most.