Yes I would put money on the Graphics Card Memory acting up. Probable cause is damage from a bad PSU. Check the PSU out and make sure it is not faulty before replacing your Graphics Card. I suspect your PSU has damaged the GPU's RAM.
I agree with dndhatcher. Try to get into safe mode. It uses the windows default driver there. That will rule out or confirm the driver as an issue. Though, you have some pixelation in the BIOS, so I'm thinking there is a hardware or maybe a clock setting issue.