My Mac Pro 3,1, A1186 EMC 2180 is displaying weird screen artifacts, and, although it chimes, it will not load OS X. It does not seem like it is advancing past apple EFI. My current Graphics Card is an nVIDIA GeForce 8800GT. I have pushed this card to the limit (mainly with rendering 1080p videos, but also many 4K Ultra videos), so I'm wondering if it is causing the issues. Actually, I just assume that CS6 utilizes GPU Rendering, although CS6 is a bit outdated. Even if it doesn't, it's still probably pretty hard on the old GT to work with rendering 1080 and 4k videos, many with basic 3D effects. I'm bringing this up because I believe it to be a dead Graphics Card. If I'm mistaken, and these symptoms seem like a different (maybe even cheaper, Graphics Cards for heavy Graphic Design are expensive) issue, what else could it be?