Hi all, I'm running a MacPro 2,1 on El Cap. It ran great for over a year, until about 2 months ago when bang the video went out. At the time I was running a Radeon HD 5770. I swapped in a GTX 650 ti from another MacPro 1,1 I have, and the 2,1 Mac Pro ran OK with that card. I had some intermittent problems starting up with the GTX 650 card installed, but for 2-3 months I was always able to get a successful boot. Last week, when I tried to boot from an external HD (also El cap), I've no longer been able to get the 2,1 to startup. I installed both video cards into the 1,1 MacPro, and that won't startup either!! Is it possible that my 2,1 has fried both cards? Any ideas on what might be happening, and/or how I could confirm that my video cards are good/bad?