There have been lots of threads on various forums recently about the effect or not of varying PCIe bus speeds on folding performance, gaming performance does take a hit on lower speeds due to bandwidth but does the same hold true for F@H? A previous attempt to test this on my Z9PE rig failed as the WU kept dumping when i changed the GPU into a different and I had no access to a PCIe 3.0 x16 slot due to the CPU's fitted, with my new rig I can now do at least some tests.
Speeds tested will be PCIe 3.0 x16, PCIe 2.0 X16 and PCIe 1.1 x16, this will give us numbers for 3.0 x16, 2.0 x16, 1.1 x16 and 3.0 x8 as bandwidth is the same as 2.0 x16. All tests will be run using FAHBench 2.2.5 and a single WU that was downloaded and run for 15% at each bus speed.
Results were as follows
OK, 1st test on an actual WU - haven't had a chance to do any proper testing as win7 won't install properly and windows is a lot easier to run a bunch of WU tests on the Linux. This is taken from my hfm logs on my main folding machine running the zorin 9 distro.
PCIe 2.0 @ x16 project 10490 tpf 2.40 to 2.42 on a GTX 970. PCIe 3.0 @ x16, project 10490 tpf 2.40 - no change between PCIe 2.0 and 3.0 x16 at this time - this bears out the gaming performance speeds found elsewehere.
PCIe 2.0 @ x8 project 9151 tpf 1.13 to 1.26 on a GTX 980ti, PCIe 3.0 x 16 project 9151 1.07 - 6 second change between current and previous recorded minimum time - this takes ppd from 422k PPD to 479k PPD. Again the gaming performance speeds do show a drop off at PCIe 2.0 x8
As projects run through over the next couple of days i'll post more results and try some PCIe 1.1 tests but early indications are that PCIe 2.0 x8 and below do affect performance and the faster the card the bigger the hit.
Speeds tested will be PCIe 3.0 x16, PCIe 2.0 X16 and PCIe 1.1 x16, this will give us numbers for 3.0 x16, 2.0 x16, 1.1 x16 and 3.0 x8 as bandwidth is the same as 2.0 x16. All tests will be run using FAHBench 2.2.5 and a single WU that was downloaded and run for 15% at each bus speed.
Results were as follows
OK, 1st test on an actual WU - haven't had a chance to do any proper testing as win7 won't install properly and windows is a lot easier to run a bunch of WU tests on the Linux. This is taken from my hfm logs on my main folding machine running the zorin 9 distro.
PCIe 2.0 @ x16 project 10490 tpf 2.40 to 2.42 on a GTX 970. PCIe 3.0 @ x16, project 10490 tpf 2.40 - no change between PCIe 2.0 and 3.0 x16 at this time - this bears out the gaming performance speeds found elsewehere.
PCIe 2.0 @ x8 project 9151 tpf 1.13 to 1.26 on a GTX 980ti, PCIe 3.0 x 16 project 9151 1.07 - 6 second change between current and previous recorded minimum time - this takes ppd from 422k PPD to 479k PPD. Again the gaming performance speeds do show a drop off at PCIe 2.0 x8
As projects run through over the next couple of days i'll post more results and try some PCIe 1.1 tests but early indications are that PCIe 2.0 x8 and below do affect performance and the faster the card the bigger the hit.