Mac Pro 2008 will not boot and no video out I have a friend with a mac pro 2008 model - which is failing to boot.  Windows 7 was the predominantly used OS on it, and she hardly ever booted into OSX Snow Leopard.  She did change the graphics card at one point, but I dont think she booted into osx once after installing the replacement gfx card (xfx 6870).  

She tried to boot into OSX by holding the option key - but just received a blank screen and no video output.  When booting into windows, and selecting the 'boot into osx on reboot' option - now there is no video output at all - and no option to select boot OS - so we're really stuck now.  There are two chimes on boot.

I really have no experience with Macs - and have no idea where to start troubleshooting this problem.  Any help would be appreciated!

Edit:  I have done some reading and possibly the reason there is no video is because the xfx 6870 model has not been flashed, and doesnt support the efi-bootcamp menu.

Edit: Are there any keyboard shortcuts to select the OS on the bootcamp os select menu? 

Edit: Finally got windows 7 booting again after digging out the broken 8800GT.  Now just need an idiot-proof guide on flashing the 6870 so it works in osx!

Edit: After doing some reading - it appears that the last version of snow leopard should have support for the 6870 - so I will probably try booting to OSX with the old card, then running the system update - and hope that the old gfx card does not fail completely during this time.  Then - if we can boot into OSX with the 6870, we will try using this zeus tool http://www.groths.org/?tag=zeus - which appears the easiest way to flash the card.
You could try setting the PRAM. I think that was still effective on those models. But you are probably right about the graphics card. You can still pick up "cheap" cards from places like Powermax or powerbookmedic or owc