Originally Posted by maarten12100
1 no hit whatsoever plenty of bandwidth
I'm sorry but you don't understand how the relation of PCI-E with graphics cards works. Bandwidth saturation is not (directly) the issue. The issue is latency. In fact, the irony is that bandwidth of PCI-E 3.0 X16 is extremely low compared to modern VRAM and that is the reason VRAM must reside on the graphics card rather than on the main system. We WOULD have saturation issues if it resided there but we know it sucks to be there so it won't.
But, the main reason we need as many PCI-E lanes as possible is latency
. It doesn't matter than you have 10GB/sec and only 100KB to transfer. That 100KB will transfer faster
on 100GB/sec bandwidth,rather than on 10GB/sec.
i.e YOU WANT
as much PCI-E bandwidth as possible, and X16 is not 100% of it
, it can even use 999X lanes and still see a benefit
due to the low latencies that would mean (well, unless 999X hits some quantum mechanical limits but that's irrelevant to the general point).
Of course, graphics cards have other latencies as well, and since above X20 lanes on 3.0 PCI-E the latency is already low enough for them, it will be unlikely the main bottleneck. But, it's a fundamental mistake to talk about saturation because that is not the issue at all.