Grey screen of death (possibly)

Mar 13, 2018

  • I5 4690K
    AMD R9 280X
    MSI Z97-G55 SLI
    Corsair 8gb dual channel RAM
    EVGA supernova 750 G2
    Stock CPU cooler
    Windows 10 64 bit

I've checked most related threads to this issue that I am having. For some time I've been having the occasional vertical lines appear after strenuous tasks e.g. closing total war: Warhammer that is heavily modded (don't play it any more lol).
The first instance of grey screen occurred during a round of Insurgency where the sound also locked on the most recent sound. Windows would not boot.

After this happened I booted in safe mode and ran powershell and used these commands: SFC /scannow & Repair-WindowsImage -Online -RestoreHealth
Restarted with no issue (the bars that were appearing even over the BIOS screen had disappeared).

I then ran DDU in safe mode, restarted, and reinstalled the latest driver.
I thought I had solved the issue, but the same thing happened even while watching youtube clips. After I rebooted and did the same process with powershell, it booted the OS. But green pixels did float around for the first 30 seconds in the full OS.

I have checked temperatures using cpu z and gpu z, and adjusting fan speeds in BIOS. I am about due to change the heatsink, but I doubt temperature is the issue here.

Any ideas?