Hi all Seeking some advice. PC specs are per my sig. PC has been running fine then came back to my PC yesterday and screen was black as if no signal and non-responsive but PC still running. I rebooted several times but the PC failed to POST. Initially I had thought it was my graphics card as both fans were not running but would perform a small ‘twitch’ every 4 seconds or so and then stop. I swapped this card with an old one and was able to boot into Windows again fine. I have since reinstalled my current graphics card and installed the latest nvidia drivers and PC seemed fine for an hour. I came back just now and the screen is black again and the card fans are ‘twitching’ on and off again. Edit: I just read some EVGA forums and apparently the idle fan 'twitch' is normal for the card. I ran MemTest86 v4.20 and it found 48 errors after 7 passes overnight. Below is a screenshot. Note all four Corsair sticks were inserted when I ran MemTest so I still need to diagnose further Are you thinking RAM is causing this locking up or some other additional issue?