My venerable mac pro 3,1(2008) was left dead after mavericks installation. I was doing a clean install onto a separate HD partition. I left the installation during the transfer from my old Snow Leopard partition. And when I came back, no video signal from my Apple Radeon 5750 HD. Not via the display port or via DVI. It still seems semi functional, I can eject the DVD drive, but even attempting to boot off the SL install DVD yields no video signal. It does seem to boot off the DVD, but I can't verify it obviously. I suppose my video card could have chosen that exact moment to die, but I'm doubting it. Any ideas what to try next.