How constrained would a 7950 be at PCIe 2.0 x1?

[chucky2]

It seems like PCIe 2.0 x1 would be somewhat the equivalent of using Thunderbolt to communicate to an external box with a video card in it. I'm wondering, has anyone ever done benchmarks on how much of a performance hit one would take doing this?

Chuck

P.S. I spent like 5 minutes looking into this last night, so if I'm wrong on the PCIe 2.0 x1 to Thunderbolt comparison, please correct me!

 

[Yuriman]

Check here: http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/3.html

Seems to vary a lot from game to game, some suffer almost none going from 3.0 16x to 1.1 4x, but I suspect 2.0 1x would be brutal.

 

[Stuka87]

performance would be absolutely horrible. If you look at the video cards designed for 1x, they are very low end, like 5450's and such.

 

[willomz]

Thunderbolt has plenty of bandwidth.
EDIT: Sorry, not for GPU, not on current specs, but next year we might be getting close.

 

[FalseChristian]

How come I upgraded to Z68 and Sandy Bridge and now I'm stuck at PCIe 2.0 x8 when before this I had a shiity E8400 on a low-end Asus P5N-D and I was getting PCIe 2.0 x16 on both cards?

 

[KompuKare]

Actually it's that bad although as usual it does depend on which game etc. THG did a review
http://www.tomshardware.com/reviews/pci-express-graphics-thunderbolt,3263-7.html

While they used a desktop mobo with Thunderbolt rather than a laptop, it should give you an idea.

 

[AdamK47]

How come I upgraded to Z68 and Sandy Bridge and now I'm stuck at PCIe 2.0 x8 when before this I had a shiity E8400 on a low-end Asus P5N-D and I was getting PCIe 2.0 x16 on both cards?

Sandy Bridge = Controller on the CPU with 16 PCI-E 2.0 lanes.
Core 2 = Controlled by the motherboard.

Sandy Bridge E has 40 PCI-E 3.0 lanes.

 

[FalseChristian]

Sandy Bridge = Controller on the CPU with 16 PCI-E 2.0 lanes.
Core 2 = Controlled by the motherboard.

Sandy Bridge E has 40 PCI-E 3.0 lanes.

Thank you for the explanation. How much will this impact gaming performance?

 

[kalrith]

I had a problem with my 4870 running at PCIe x1 (although I'm not sure if it was 2.0). My 3DVantage scores more than doubled after fixing the problem and running it at x16.

 

[AdamK47]

Thank you for the explanation. How much will this impact gaming performance?

I dobut there is any difference with two GTX 460s. Two GTX Titans or 690s and there is a difference.