I purchased my Power Mac G5 with dual 2 GHz cpus, 2.5 GB of memory along with a 20" Apple cimema display. All parts came with computer from Simly Computing. From day 1 I have had these intermittent problems with not only wake up but also start up problems. After trying:
Resetting PRAM,
Resetting PMU,
Repairing Persmissions,
Upgrading to 10.4 (from 10.3),
Running Tech Tools Deluxe ( lost access to 2nd Hard Drive).
Some days, I actually had to restart my computer 10 times before the monitor would come on. I can hear all the things like HD, Fans, clicks on the monitor, lights on the Keyboard and mouse, but still have a blank monitor.
One day after 12 start ups, I took my monitor down to London Drugs, the only store selling Apple products. They plugged it in and it started the second try.They would not send it back to Apple without me getting a work order number. I took it home and it started for about 1 week with out a problem. The next time it took 6 tries, with start I connected my old CRT screen as a 2nd monitor and had no problems ups. After two weeks, I needed the CRT on my windows PC. Then started to get the no start up again problem on my G5.
I redid the above checks and now I am getting 95% good start ups. However, if I let the G5 go into a deep sleep, (no fans) I end up getting black and green lines on my monitor and have to restart. To think I bought a Mac because of its reliability.
Please let me know what else to try!
I also have a Wacom Intuso II which may be causing the problem