Power Mac G5 will not boot. No Chime, Black Screen, Solid LED.

Came in this morning, plugged it in and of course it started up. I did notice however that the fans were running louder than usual and continued to rev up and down frequently. So I restarted into OF and entered all 3 of the commands you listed. This time all three worked with no problem. When the computer rebooted, oh wait, no it didn't reboot. Seems my window of opportunity is getting smaller and smaller in regards to "up time" with this machine. I'm sure the commands worked however the machine is now back to the non-starting state.

So I moved onto step 2, inspecting the Mac. The iPhone4 was particularly helpful here since the flash lights up the insides of the computer quite well and lets you fire off a few snapshots. (It also took even better video of everything.) I'm attachign a photo of what I found. (Here is where you act shocked). I found quite a bit of yellow crud formed inside as you can see in the photo. So yes, this computer does have the typical Liquid Cooled G5 leak (aka LQ G5 Killer). I believe this is what killed my last liquid cooled Mac. That one however went out in style. Loud crackle, smoke (smelled like electrical), UPS alarm, etc. Fried everything from the Power Supply to the Logic Board and Processors (according to the authorized Apple repair technician who inspected it). It's starting to look like it's time to bury this computer alongside my last one.

I reviewed the Liquid Cooled G5 Overhall documentation and I have to say that's way beyond my ability level. I don't have the tools, and messing with thermal grease, coolant, O-Rings and hard to find replacement pins seems a bit out of my league.

I guess at this point my best bet it to salvage what I can as TechTools confirmed that the video card, ram, and other devices are still okay. Do you have any other recommendations at this point??

Here is the photo I took of the inside:

Here is a closer shot of the inside. Is this build up from a coolant leak?

After viewing the guide to removing the power supply I decided to go with option 2. As a preventative measure I grabbed a can of air and directed it towards the fan openings. I did see a bit of dust blow out the back so it was a worthwhile exercise. The rest of the computer was very clean on the inside as I do regularly dust it out however I never thought to direct the canned air into the bottom power supply fans. Thanks for the tip.

So now I will wait and see how many more restarts I get. With a little bit of luck I can squeeze a bit more life out of this machine.

Well, as we thought my success was short lived. This morning I shut down the computer as I wanted to reformat and put a fresh OS on it. When I pressed the power button to turn it back on I heard the click you spoke about, heard the fans whirl up and down, the chime but then nothing. No further activity from the Mac. I'm just faced with a black screen and if I let it sit for a few minutes the fans increase in speed until it sounds like the Mac is going to take off. So here we go, troubleshooting round 2. Here's what I know:

1) The Mac is plugged directly into the wall so I know it's not a UPS, only the keyboard, mouse and monitor are plugged in.

2) When it was up yesterday I ran a full TechTools scan on the Mac and it passed with flying colors so all the ram checks out, video card checks out, etc.

3) I have a fresh CMOS batter on the motherboard.

4) I blew out any remaining dust from the case and the power supply.

5) The LED light above the power button stays lit solid white

6) I tried a new power cord

7) If I look throught the front of the case I see a red light inside. Not sure if that's helpful.

8) Unplugged the Mac, held down the power button for a few seconds, opened it up and pressed the SMU Reset button on the motherboard.

Obviously nothing I tried changed my result. I still just hear the click, fan whirl and chime.

If it were the power supply that was bad would I get this far? Would a dying power supply still power up the fans to full speed?

Any ideas of where to go from here?

Thanks again for your help.

When the computer fails to start up (black screen or now sometimes hangs at grey screen with apple symbol), I can see a red LED through the front of the computer. If I open it up I can't see it because it is behind the pull-out fans or possibly behind the processors. It is somewhere to the right of the upper bank of DIMS. Information I've seen online say this is a light for the Manufacturer's use and can be safely ignored. (Not so in this case.) You can see it lit up through the 2 lower DIMMs of the upper bank if you are looking through the front of the case. It's hard to tell how far back it is because it's dark in there but it's definitly behind the upper bank of DIMMs.

One of the times it booted up I tried your firmware reset. The first line "reset-nvram <cr>" returned a message about reset being an invalid command. I tried it several times exactly as you had it but it didn't work. However, the second line seemed to do something as it restarted the computer.

While it was up I also did a fresh installation of Leopard (full, retail version I bought for this computer a few years ago) so we can eliminate any possibility of it being sofware related. It rebooted and I finished the set-up. I figured this way we could rule out something wrong with the OS. Still the issue continues. Sometimes it starts up, sometimes all I get is a chime and fan whirl and other times I get hung on the grey screen with Apple logo.

When it fails to start up I've found unplugging the Mac, waiting for a while (hours if not a day) and plugging it back in gets it to come back. (It may just be the time and nothing related to it being unplugged, I have no way of knowing). At the moment I am back to fan whirl, chime, black screen, no boot, red LED I mentioned above. Therefore my Mac is sitting unplugged waiting for the next step.

Thanks again for your assistance with this. Please let me know what you think I should try next.