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I've confirmed on another computer that my monitor works. The DVI cable works. My Mac Pro does successfully boot up (I hear the start-up chime, as well as the Gmail "new email" notification chime).

But I can't get an actual screen to show up on my monitor.

I have two video cards (ATI Radeons, Apple issued. 4 DVI slots total). I've tried each slot. No dice.

Any troubleshooting suggestions?

My setup was working just fine when I last put my computer to sleep. Stopped working when I woke it up.

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which 2 video cards are you using? – deddebme Aug 26 '09 at 4:35
ATI Radeons. I took out one of them, moved the other to an unused slot. Still no display. Is it really possible that both of them burned out? – Aaron F. Aug 26 '09 at 4:43
Are they both apple versions of radeon cards? – Troggy Aug 26 '09 at 14:52
Yes. Original hardware. I haven't changed anything since I bought the computer. – Aaron F. Aug 26 '09 at 15:36

Went down to the Mac repair store.

Turns out both my ATI Radeon video cards had burned out. (Power surge, perhaps?) Getting a new card fixed the problem.

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