My PC started glitching out like this and I don't know how to find the cause.
Columns of red lines dominate the screen, and certain characters aren't being displayed during startup. This happens with every operating system and every monitor. I can only get into the OS in recovery mode.
Did my CPU get fried? My motherboard? GPU? Corrupted BIOS? How can I find out?
That looks EXACTLY like my R9 280X did when it died. My solution was to put it in the oven, which brought it back to life, and then running it undervolted and with an aggressive fan curve to make sure it stays cool.
Can this also happen as a power supply is starting to go bad or if your PSU isn't big enough for all your cards? Seem to recall something similar ages ago.