Unknown artifacts and crashes

[Theosaurus864]

A day or two ago I started getting crashes whilst using my pc, specifically using blender. I use blender frequently and am used to crashes where the pc needs to be restarted, or where the system freezes, or the program times out etc, however within the past few days I have been getting crashes which cause artifacting and my pc to no longer output to my display. A restart of the pc fixed the issues any time they occurred however today after this problem occuring earlier in the day I restarted and everything seemed fine, my pc was working fine it seemed. I installed a program and restarted my pc later in the day however and now what look like artifacts are present on my display. I have restarted my pc several times and the artifacts still remain, updated my GPU drivers too and this did not solve the issue. I have no idea what could be causing them or how to fix the issue. Any help would be greatly appreciated. The files attached show the artifacting on the desktop it is hard to see however they are present and if and more visible with certain things on the screen etc.

The issues don't appear when loading into windows, however once I reach the lock screen they are present.

My pc specs are- intel pentium G3260, 8 gb's of ram and a gtx 760. All are running at stock speeds, the GPU has an overclock from the manufacturer but no after market over locking has been done. 

(Edit removed GPU and the artifacts are gone so am guessing my GPU is dead if anyone has any other ideas or suggestions would be greatly appreciated as I'd prefer my GPU to not be dead but that's the only reason I can think of other than the power supply being faulty for the pci-e 6 pin power but I don't have another power supply to test)