Hi, I have a question regarding my Samsung NVMe SM951 m.2 drive, I have bought it because of the super speeds and made sure my motherboard supports it, I have Asrock x99m Fatal1ty Killer 3.1 PCIe Gen3 x4 M.2 and people getting 1.3GB/s, I can achieve this but ONLY if the CPU is maxed out! Normally it will be between 850 - 950MB/s under low CPU load. This is the latest driver I can find online I'm running HD Tune to check the speed of the drive Why the heck does the drive only peak performance when CPU is higher?
I mean there is a direct correlation between the speed of the drive and the load of the cpu, the higher the CPU load the faster the m.2! (between 850 - 1350MB/s) Say for instance the cpu is idle the m.2 will peak at 850MB/s, if I convert files and have the cpu load at 50% the drive will increase to 1000MBs, and if I have the CPU load to max the drive peaks to 1350MB/s
Might be something to do with SSD load type also. You can easily test this by putting CPU some dummy work, like Prime95 running on small/large amount of threads and see if that shows similar results.
Try that first and see what happens. If CPU load does not affect speed, then it's more load type question.
I've just done a test video for you, notice the drive maxes out ONLY UNDER CPU LOAD https://1drv.ms/v/s!AsFTmtIhOSgtizgeJUk3sCUoDc2y And this is the final result of the test, the peaks are where I ran video conversion
I thought maybe it's speed step boosting CPU speed to 3.5GHz from 1.20GHz but no, it's constantly 3.2ghz during the test
Perhaps it has something to do with CPU's PCI Express controller. Other than that I have to admit I'm out of ideas.
You can also try if better cooling helps. That drive overheats. Also if CPU load goes up, it probably gets more cooling and work faster.
ive heard it throttles so easily, but the changes are way too fast for it to cool during cpu load. besides I have water cooler and fans dont change so rapidly It's like a switch, it suddenly peaks for no apparent reason under cpu load so I thought its a power saving thing in the CPU so I disabled C1 state in bios to no effect
since the drive uses PCI express 3 x4 could it be the PCI pathways slowing down, possibly under power saving, slowing it down?? if this is the case what shall I be checking for, something in bios? - I don't understand c1 states and stuff
Perhaps Windows power saving options may also help? Hard to say where to look in your BIOS because all BIOS's are different.
okay, I just done a power report using powercfg -energy to check the Active State Power Management which controls speed and power consumptions of the PCI-E controller, it's set to disabled https://en.wikipedia.org/wiki/Active_State_Power_Management
had a thurough look in bios, changed pci slots to gen3, the ASPM was already disabled. i also tried setting multiplier to x37 (which is normal on this cpu) but the thing didnt boot (??) im out of options
I also don't have further ideas. Might be software/driver issue. If is, then it's much harder to solve.
