There's this person who owns an old first generation Core i CPU and he's planning to buy a new GPU to couple with it.
He was wondering if the current flagship GPUs available right now in the market like the R9 290x and the GTX 780 Ti would saturate the PCIE GEN 2.0 slot on his current motherboard. Will it saturate or will it just work normally with out any performance dip as if it wasa PCIE GEN 3.0 slot?
The difference is incredibly marginal, you won't see much of any performance hits, the only thing would be his current processor. It can hold its own, but getting a top tier card for his system seems a little wonky :/
Some cards get close to saturating the PCIE 2 interface when running at 16x. Now, if you were to be running an SLI/XFire setup then you are probably running both PCIE slots at 8x, halving the bandwidth for each card. Now, PCIE 3 is double the bandwidth of PCIE 2 meaning that PCIE 3 running at 8x is the same speed as PCIE 2 running at 16x. That's where the current benefit of the tech is until later on when cards start to push past the bandwidth of PCIE 2. I hope that all made sense.
Well i dont realy see that as a benefit, unless you talk about X79.
But for Z77/Z87/Z97 it does not make any diffrence, because they only have 20 pci-e gen 3 lanes natively. Which is basicly the same as the 40 pci-e gen 2 lanes on 990FX chipsets for example.
I think some high-end, dual card configurations can saturate PCIe 2.0, when those cards are running in x8 x8. However, the performance difference is negligible. You will be fine with any single card x16.
The 780ti and R9 290 will be held back a little by that processor. You could use a 780ti, and have much of the performance. Something like a 280x will be more balanced.