Hard Disk Monitoring

So I've been getting very slow loading time when playing games and decided to test the SSD with Read Surface Test. The result is that it is at 100% health and all sectors show light green indicating no bad sectors. What puzzles me is the transfer speed is not constant and vary wildly, sometimes reaching as low as 5 MB/s even though it is a SATA SSD that should be close to 500 MB/s in transfer speed. Is my SSD getting bad? Is there anything I can do to fix this or should I replace it?

> should be close to 500 MB/s in transfer speed

Sorry, but I'm afraid this is wrong assumption.

Manufacturers like to say "speed is up to XY MB/sec" but they never mention that it is NOT always true and with time and normal use, the performance is constantly decreasing.

What you see is completely normal and expected: SSD transfer speeds can vary and can be even really big drops, even on a perfect drive.
There is no guaranteed minimal performance level, so the speed can drop (but 5 MByte/sec is really low, I agree).

I suggest to try Disk menu -> Extended self test in Hard Disk Sentinel. The internal hardware self test of the SSD usually helps to "refresh" the data of the slower areas and then the performance may improve. This depends on the actual SSD and firmware, some drives may benefit from this step.

Would be interesting to see its complete status, so I suggest to use Report menu -> Send test report to developer option, it may give some ideas/thoughts about the really low value you saw.

Oh that's a bummer. I thought because it's a Read Surface Test, the speed shouldn't vary that much because it is not affected by cache. Regarding the Self Test, I've done the Short and Extended test and couldn't find any error. I'd try to do that again and see if I could find something.