We previously reported on a problem with some currently shipping Power Mac G5s where a cold-start (the machine is off, then booted) results in a blank screen from which the user must manually reset via the Command-Eject-R key combination for normal startup to occur.
We've now hear from some users who have had success eliminating this problem by using the age-old process of resetting PRAM. MacFixIt reader Robert Cramer writes:
"I have the same problem (blank screen from cold start) with my dual-2 GHz Power Mac G5 and have resorted to zapping the PRAM by selecting Option-Command-P-R immediately after switching power on. The procedure is in the Troubleshooting section of the G5 Manual."
In this case, it may not be the actual zapping of the PRAM that is doing the trick. Performing the PRAM reset causes your Mac to restart continuously until you release the key combination. It may simply be the repeated restart that is allowing users to startup properly.
Meanwhile, a report from Frans van der Geest indicates that the problem was temporarily fixed by removing, and then re-installing his RADEON card.
"A suggestion from Apple to remove and then re-install the video card seemed to work to fix the problem with a black screen when booting my Power Mac G5 'cold' at the beginning of the day. It booted up with the screen working for two days. Today, the first startup was black again: no video was initialized. Restarting directly again and the video was there again."