I recently got a new HDD for my pc the WD 1tb black caviar my previous one was a 500gb seagate 7200rpm drive and it didn't have this problem i have 4 drives in my pc ill go ahead and list my system specs:
EVGA SC+ GTX 680
16gb sniper series RAM
Boot Drive: 64gb crucial M4 SSD
Storage Drive: WD 1TB Black Caviar
Back Up Drive: SG 1TB 7200rpm
Server Storage Drive: 500GB SG 7200rpm
The WD keeps disappearing after awhile i never turn off my PC or put it to sleep mostly because i run a few servers but that didn't effect the old drive, I checked the cables they are fine its in a 5.25" hot swap bay in the NZXT Switch 810 i tried swapping the sata cable that didn't help, i Googled around found alot of threads on this issue but none of them were my answer .
I've noticed this usually happens when I'm away for long periods of time like to go to sleep or go out so i suspect some sort of hibernation or sleep causing this problem.3
Also can someone link me a good speed test for my SSD/HDD?