PCI 2.0 vs 3.0 bottleneck?

[Arreo]

So I have an Asus Sabertooth x58 and it is currently running two EVGA nvidia 460s in SLI. I'm thinking about upgrading them since I got one of the $300 2440x1440 Korean 27" monitors (man is it nice).

I was thinking of upgrading to a 7970, but my question is since my motherboard only supports PCIe 2.0 x16 and the 7970 run on PCIe 3.0. I assume that a 3.0 card is backwards compatible but is there going to be a major performance hit? Is it worth doing the upgrade?

I vaguely remember a article on Toms about this issue, but I think that it was pretty old and examined the differences between PCIe 1.0 and 2.0.

 

[maestro0428]

No, there will not be much of a performance hit. Unless you are have issues with your SLI, one 7970 will be lower in performance than your two 670s.

 

[FunSurfer]

2x670 is way better than one 7970

 

[FunSurfer]

Anyway, the PCIe 2.0 x16 is a small bottleneck (about 2-5%) for GTX690.

 

[Derza10]

he ninja edited his post the 670's are now 470's. You won't see a performance hit with PCIe 2.0.

 

[Arreo]

No, there will not be much of a performance hit. Unless you are have issues with your SLI, one 7970 will be lower in performance than your two 670s.

Sorry, I totally completely mistyped that. Epic fail on my part.

Two 460s in SLI

 

[Arreo]

Thanks for the advice everyone, even with my epic fail.

 

[willard]

No card currently needs the bandwidth offered by PCIe 3.0. You get something like 85% of the performance of a GTX 690 on PCIE 1.1.

Generally, any video card will work fine in any motherboard, so long as your board is reasonably recent (not more than 5 years old, for instance).

 

[lpedraja2002]

Haha I was wondering if those guys actually read the original post correctly lol.

Here's a very nice article from HardOCP measuring performance difference between the two specifications:
http://www.hardocp.com/article/2012/07/18/pci_express_20_vs_30_gpu_gaming_performance_review/1

In conclusion... the difference is so minuscule to it's not even worth mentioning.

 

[LW_Black4]

To take advantage of PCIe 3.0 one needs a compatible cpu (e.g. Ivy Bridge), mainboard (e.g. Z77 chipset) and video card (e.g. HD 7000 series and GTX 600 series).

Performance gains for PCIe 3.0 hardware are modest at best, so it's not compelling to go out and invest in all that gear if you have a perfectly good system now. In the HARDOCP article referenced above, the conclusion is summed up nicely with the comment "There was no instance where performance differences allowed us to improve the experience on the Ivy Bridge platform over the Sandy Bridge platform."


If you're building from scratch now it makes more sense, and PCIe 3.0 compatible gear is modestly more expensive at retail.