dstarr3 :
Is there anything that's been close to saturating the bandwidth of PCIe 3.0? GPUs don't even saturate 2.0, and I don't think SSDs are that fast yet.
Even at launch, there was a small but measurable difference in performance between fast GPUs in PCIe 3.0 slots, compared with the same system in PCIe 2.0 mode (some BIOS' have a PCIe version setting, which can enable a direct apples-to-apples comparison). GPUs have only gotten faster, so you should now see a substantial difference.
As for other peripherals, including SSDs, there are two benefits. First, by increasing the speed of each lane, you can reduce the number of lanes required. This lets peripheral manufacturers either increase speed, or reduce the number of lanes, thus lowering costs and allowing users to fit more peripherals in the same system.
Second, if you increase the speed, not only does it increase bandwidth, but it also decreases latency. Lower latency can improve performance, even in cases where the bus isn't 100% saturated. This probably accounted for the original benefit to GPUs. And lower latency obviously benefits realtime applications, like VR.
SteelCity1981 :
how did the samsung sm961 reach pci 3.0 x4 useable limits when its bandwith was 3,100mb's yet pci 3.0 x4 3.938gb's? there is still 838mb's unused.
I don't know the details of the quoted performance measurement, but you
might find a slight improvement by increasing the bus speed, simply due to the lower latency or less impact from transaction overhead.