# g5 dual 2.5 mac won't boot



## discoboy (Jul 1, 2006)

the core of my home studio is built around a g5 dual 2.5 ghz mac tower.  it's AC is plugged into a furman power conditioner (this one, to be specific), which is rarely turned off.  this machine was purchased in january of 2005.  

recently, while the mac was in sleep mode, the power conditioner was turned off.  this may be the first time the AC was cut before going through the shut-down procedures.  when i discovered this,  i tried to reboot the computer with no success.  as soon as the mac had power to it,  it's front LED was on at a constant bright glow.  however, no combination of tricks (holding the startup button for an extended period, plugging it in with my finger on the startup button, etc.) would get the machine to do anything at all.  the fans do not start, the disk does not spin, the LED does not change.  the machine is as silent as it was when it was unplugged.  

if i unplug it, the front LED dims out after a second or two.  once plugged back in, it's back up to full brightness,  with absolutely no change no matter what i do to it.  if i take the side panel off, no fans start up, nothing changes at all.  at no point does it send any signal to the monitor, none of my peripherals show any sign of connection to the machine, literally NOTHING HAPPENS.  

i've read on this forum about PMU issues and CUDA resets, and it sounds like that could be the root of the problem.  however, from the apple support site, it would almost appear that my model does not have a "switch" to reset (not that i've dug into it to look, i'm assuming that it's a "late 2004" model), so where would that leave me?  i've certainly already unplugged it, hoping it would reset itself but to no avail.  

just about anything else i've read indicates problems i can only fix IF the machine would boot.  i'm at a loss, can anyone help?  

thanks for reading this...

cameron


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## bobw (Jul 2, 2006)

Try resetting the SMU


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## kenny (Jul 2, 2006)

I had a G5 (single 1.8, but still) do that recently after a failed firmware update, and the fix that worked for me was to pull the CMOS battery and leave it unplugged for 24 hours or so. Afterward, MacOSX complained bitterly about the clock being set to somewhere in 1969, but after resetting that, it's been fine.

Good luck!


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## discoboy (Jul 5, 2006)

thanks to the both of you.  removing and reinstalling the battery did indeed fix the problem.  i was worried that it was going to be an expensive repair.  

cameron


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## CRP1 (Mar 27, 2007)

I have a G5 tower that won't start. I tried installing the start up disk and can't get anything to come up. I've tried holding down every key I have read about. 

In the beginning the G5 was on and running extremely slow. I was working on a rather large file and it kept locking up. When I tried to restart it, the flashing the mac ? mark logo appeared. Tried the start up disks and nothing. Any suggestions?

Thanks


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