1) Check G5 with ASD.
2) Move cpu1 -> cpu2 socket and cpu2->cpu1 socket(i had similar issues and this helped)

[ Edited by zukow 11.10.2018 - 14:45 ]

Does it give any sound?
Does the white LED blink?

I'd try zukow's idea - it very much reminds me issues that I had when replacing CPU modules.

Thanks for the hints folks,
@Amigaharry2 - I have not that CF2IDE hardware, usually when I need an emergency/recovery boot I simply use the MOS installation CD though. Anyway, I don't think my system reaches the loading stage of boot.img, because when this issue happens the monitor remains in standby mode, which is still a very early stage AFAIK. Also, when this happens I think I can't hear the noise of the HD spinning, that's why I suspected it was related to the HD

@koszer: no, no sounds and no blinking

@zukow: uhm ok I still have the ASD image to burn, I will check as you suggested. I will also try to swap the CPU modules once I have some time for it.

Thnx

Update: the guy who sold me his PowerMac also had given me a link to download the ASD 2.5.8.dmg... I decided to burn it but after three attempts I gave up. The CDs seem ok but my PowerMac refuses to boot from them. Even by opening the boot menu with ALT I can't see the ASD cd as a boot option... so I can't pursue this avenue.

So it's time to swap the CPU modules then apparently :(

If the machine doesn't work even after CPU swap then I can send you some (well, maybe all of) spare CPU cards that I have. At least some of them should work. But you will need the ASD anyway, to do thermal calibration.