Mac Pro (2008) black screen when idle

[cezanne1204]

My Mac Pro has started to go to a black screen when idle for a period of time. When it does this, I need to use the power button to power off and restart. It does not appear to be asleep (I have it set to never sleep) since Time Machine is still backing up and Mobile Me is still syncing. Oddly, if I manually put the computer to sleep (under the apple), it will come back to the normal screen by using a key on the keyboard (moving the mouse does not work) no matter how long I am away.

I have tried resetting, disconnecting and reconnecting all cables but the problem still exists. Any help or thoughts is appreciated. Thanks.

[dmadill]

I have a similar situation.
Mine begins at startup.
Occasionly it is fine.
Otherwise it never lights up, and can only be "fixed" by turning off and on with the power switch.the hard drives, and other processes go on even with a dark screen.
Power goes thru the apple cinema display, 20 inch, and the keyboard and USB all function.
help?
thanks

dmadill

[afterhours]

Customer has an issue with a Mac Pro 2008. Apple Cinema Display. When the Mac Pro running 10.5.8 restarts, the screen will stay black (white indicator led does light). Computer is otherwise fully functional (can remote access it and fully control it from the resident keyboard). If the computer is shut down completely, then restarted, the display works upon boot.

Seems to also go black when put to sleep, then won't come back up.

Shutting down fully and rebooting invariably got the display back up.

Followup: shut down and pulled all cables. pulled and reseated the video card (ATI). Pressed the white reset button above and to the right of the video card once for one second. Put the system back together.

System maintains video signal now either from shutdown or from just a restart. Don't know if the video card is failing or just needed some love -- or if the reset of the logic board (SMC) resolved the issue. If the display behaves for a few months, we'll call it fixed.

[Rattle]

Afterhours,
Was your fix permanent? Is it still working properly?
Thx

[afterhours]

yes -- the display card was likely loose. System is fine.