Help with black screen

[macgru]

Hi i am trying to get an original mac pro to work i only have pc video cards. So cannot see a boot screen to select anything. The original video card has had it. I have tried to use transmac installer for mavericks which worked but have no idea how to select the usb drive with a black screen. When i use the original hd's i can hear it loading osx. I would use pikes boot efi but cannot access usb pen drives in virtual box with mac osx. Catch 22 comes to mind any help would be most welcome. As to how to get this machine to boot so i can see anything

 

[ActionableMango]

OSX will initialize several, but not all, PC cards once it boots up. Which PC cards do you have? Which version of OS X is loaded?

 

[macgru]

OSX will initialize several, but not all, PC cards once it boots up. Which PC cards do you have? Which version of OS X is loaded?

. Hi don't know what version which ever was used for an original mac pro. I can hear the os loading but no video. I have a mavericks version of OSX and the video cards are nvidia gt320 2gb and gt9500 1gb. I cannot boot from the usb key as i cannot see the options for selecting the usb at boot

 

[ActionableMango]

I don't know if those cards will work with OS X or not. They might. Obviously whatever OS X is loaded isn't doing so. So either the cards are not compatible or it's an older version of OS X that doesn't initialize PC cards.

To blindly select the USB Mavericks installation, you need to hold down OPTION after applying power. It will be difficult to tell without seeing anything when it is okay to let go. All I can say is when you think it is done, you can then let go of OPTION and use the right cursor key to highlight the next bootable option (hopefully the USB drive), and then ENTER to start it.

If that doesn't work, then same thing but two right cursor presses.

A bootable DVD would be way better than USB key for two reasons. One, many people including myself can't seem to always get USB keys to be reliably Mac bootable. Two, a CD/DVD can be selected at startup by simply holding down "C".