Samsung 960 EVO, suddenly random IOPS read is much slower

When bench-marking my 960 EVO with Samsung Magician it's now much slower for random IOPS read and I can't figure out why.
I have made sure I have the latest drivers etc but nothing helps.



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The only change I can remember is that I converted the SSD to GPT.
I had made one change related to PCI link power saving but reverting it changed nothing.

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Partial success.
After un-checking the top box and checking it again the speeds are restored, mostly.
Except the write speed is still slower that normal (read is higher).



When I check the drivers for the controller I see something odd but not sure if it's wrong or not.
The driver version seems correct but I thought iaStorAC.sys was for RAID/Optane?





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IOPS read is good again but not IOPS write:

Yes the AC in the AHCI controller is the RAID version of the driver and yes when that driver is installed performance is slightly reduced but not by as much as your benchmark show .

To install the non RAID version , unpack your RST Raid driver package by manufacturer or Intel and then install the iaAHCIC.inf file and not the iaStorAC.inf usually found in the x64 folder of the driver , do not use the Setup.exe / msi as they usually setup the RAID one .

But now for why the read dropped so significantly , can you for starter make sure your disk did not enter a huge read / write process .

Check to see if disk read / write has high use during benchmark , you can do that by simply starting Task Manager and check the "Disk" usage % , you can even sort it by clicking the column header to see what is using the disk , usually when there is an active read / write operation this affect benchmarks .

Antiviruses , Indexing Service , System Restore services are all known to fire out of random and clog disk operation .

Hi Sineira, did you ever solve your slow random IOPS read issue? I get the exact same result as you did using the Magician, 20019, everytime now, looking back looks like it dropped down from around 330,000 to 20,000 sometime between end of 2020 and start of 2021, weird.....

Yes but not really sure what resolved it.
I removed and reinstalled drivers, maybe that was it.

Okay. I just registered for this particular topic. Just managed to put my SSD back to normal speed. I had a similar situation to the guy with the 970 EVO who posted a screenshot. My SSD suddenly started to perform poorly: 8000-18000 IOPS read/write (instead of 200,000) and transferring 1000-1500MB/s (instead of 2000-3500 MB/s).

Okay. I did all the things you guys mentioned. Updated the motherboard BIOS, switched cache on and off, disconnected SATAs, and tried to switch AHCI on, but it led to errors and blue screens. Eventually, I uninstalled a few antivirus programs, turned M.2 from x2 to x4 in BIOS, and turned on Hyper M.2 speed in BIOS too. Not 100% sure what worked in the end, but I think that antivirus protection was slowing down the SSD.

I'm writing this in the hope that it might help someone. P.S. By the way, I was talking to the shop from which I bought my SSD, and it didn't resolve the issue. I still think that malware/antivirus was the cause. I don't think that the slowdown was related to BIOS, as this SSD was fast and was giving normal performance when I installed it at the beginning (it was at the end of 2020).

You'r welcome