The other day I tried upgrading my Mac Pro 2009 firmware to 5.1. I got past the install part but when I restarted the mac to finish the upgrade I accidentally pulled out the video cord for 5 seconds then put it back in and left it in for 15 minutes but had a black screen the entire time. I don't know if the firmware upgrade went through because now I permanently have a black screen, no boot sound on startup, USB does not respond and keyboard has power but does not respond. Power works fine. Fans are working nice and quiet. Could it possibly be that the firmware did upgrade to 5.1 but because I have a quad-core 2.66 Ghz Nehalem processor it needs a different processor like a hex core Westmere to boot up. I am at a loss!