Q: Power mac g5 wont start, hardware issue?

Giving it a new Backup battery means that now it can remember. But what it remembers is garbage!

After replacing the Battery as you did, you then need to hold command-Option-P-R at Startup through three or more chimes (reset the PRAM).

I suspect a hardware problem. My 2 GHz DP G5 died years ago. They are problem prone

This is the MacBook (13-inch, 2006-2010 forum. I requiested your post be moved to the PowerMac Forum

Power Mac

And when I press and hold Option+P+R...

Are you holding the CMD key also?

CMD+option+p+r

Aren't there some more led's on the board?  What do they look like?

power supply problem?  Led?

Turning on the Mac with NVRAM battery, then put it in. Turn it off again. After that I turned in on again and I got a chime. But thats all. Turned it with a short press off again and again it was stuck. No chime. I was able to repeat that twice.

volt meter.  Be careful.

The Quad & that series had 7 LEDs,earlier ones 1 to 3 as I recall.

Hi

I have a similar problem with a G5 1.8DP. I can occasionally get it started but it will not then re-boot after shut down - the usual high speed fans. Have tried everything you have but cannot re-set the PRAM, ie it ony chimes once irrespective of how long I hold Cmd-Alt-P-R. So any further sugesstions much appreciated.

it ony chimes once irrespective of how long I hold Cmd-Alt-P-R

Many anecdotes suggest that when it will only chime once, the PRAM backup battery is dead.

Get another computer. After a while the G5 Power Macs dies like yours. I have a G5 2.0 DP in my closet with same problem.

You have removed all internal cards and peripherals except for mouse, KB and monitor?

You can try a power supply that is know to work. If still problem that would point to a logic board problem

I can only get it to chime once in a while, mostly it boots to the high speed fan issue. I have been able to get it running but it freezes after a few minutes.

Any ideas?

Try to start it with one processor and then the other. I had a similar problem with my G5 Quad and was overheating. Or it could also be power supply failing.