Power Mac G5 2.5 DP - Boot Chime But No Boot/Red LEDs on Board

[Caleb Hauge]

I purchased a 2.5GHz DP G5 a few days ago, and got a GPU for it today. The GPU is a standard Radeon 9600 and it has 4GB of DDR in matched pairs. The LCS does not appear to be leaking.

Symptoms:
Always chimes, can hear ODD & HDD spinning/initializing/whatever
No video
After about 60 seconds, fans ramp up
Red LEDs on logic board are lit, and white LED by power button stays on (no flashing codes)
When video does work, it freezes quickly - like 5 flashes of the no HDD icon before it locks up
Plugging in any peripherals beyond monitor will not allow video to come on
Will not have video if not given 10+ minutes to cool

What I've tried:
Leaving unplugged - does nothing
Leaving unplugged + resetting PMU with button and removing PRAM battery + pressing power button while unplugged - often allows it to attempt to boot, but it locks up quickly
Reseated RAM, GPU, and drives - also tried unplugging different things in various configs

What else is there to try? Any likely diagnosis? Would really appreciate any help.

 

[Doq]

Regardless of whether the LCS is leaking or not, it may have failed by stagnation (there's no more good flow).

On A1047 models, the red LED indicates that the air deflector (clear plastic cover) is not present. But if you're mentioning multiple red LEDs, then there may be a different, other issue. The service manual only mentions one red LED for the deflector.

Suffice to say, I'd check the cooler anyway.

 

[Caleb Hauge]

Regardless of whether the LCS is leaking or not, it may have failed by stagnation (there's no more good flow).

On A1047 models, the red LED indicates that the air deflector (clear plastic cover) is not present. But if you're mentioning multiple red LEDs, then there may be a different, other issue. The service manual only mentions one red LED for the deflector.

Suffice to say, I'd check the cooler anyway.

I have checked it and as far as I can tell, it's flowing. I can feel it when holding the pump and hear it. The deflector is on, and it is detecting it because the fans go nuts when it's removed. It might be just the one LED, I've read other posts of similar situations and they said it was just a reflection.

 

[Doq]

"it's flowing" isn't necessarily "it's flowing good". It might be fine, but a servicing is inevitable.

That said, it could also be other non-liquid factors, such as dried thermal compound, which will make your CPUs hot just like on air-cooled units.

 

[Caleb Hauge]

"it's flowing" isn't necessarily "it's flowing good". It might be fine, but a servicing is inevitable.

That said, it could also be other non-liquid factors, such as dried thermal compound, which will make your CPUs hot just like on air-cooled units.

I can give that a try, but would poor cooling keep it from even displaying video? I've run Pentium Ds without a heatsink before and they typically made it through at least the POST before frying.

 

[Doq]

Well, your Mac did make it through POST (that's what the chime is for).

I mention this because when I got my slightly different Quad it showed the same symptoms as your DP 2.5-- would chime, then lock up, sometimes showed video, sometimes not. If it's starting from cold then it's capable of at least starting a little bit before locking up with a thermal checkstop. Checking the cooler (and in my case, outright replacing it) was what ultimately solved the thermal problem.

 

[Caleb Hauge]

Well, I dug deeper and it’s not great. The cooler had leaked, but not enough to get outside the CPU cards. The CPUs themselves however do have a good bit of corrosion. One is corroded to the block and won’t come off. I’ve decided to use this as a parts machine and picked up a 2GHz DC instead.

 

[Certificate of Excellence]

Well, I dug deeper and it’s not great. The cooler had leaked, but not enough to get outside the CPU cards. The CPUs themselves however do have a good bit of corrosion. One is corroded to the block and won’t come off. I’ve decided to use this as a parts machine and picked up a 2GHz DC instead.

Bummer about the quad 🙁 I am curious enough to throw the corroded/stuck daughter cards in a sonic cleaner and see how it goes after that. I have a a1117 DC2ghz and it has been a great box. Congrats on that pickup. 🙂

 

[srp]

Well, I dug deeper and it’s not great. The cooler had leaked, but not enough to get outside the CPU cards. The CPUs themselves however do have a good bit of corrosion. One is corroded to the block and won’t come off. I’ve decided to use this as a parts machine and picked up a 2GHz DC instead.

I had a similar story in my 2.5 DP and I managed to clean both CPUs enough to get them to boot. I did several passes of a baking soda/water paste and an electric toothbrush, followed by isopropyl alcohol and rinsing after each pass with distilled water. Mine were corroded bad so if I was able to save mine hopefully you'd be able to save yours.

If you're parting it out and willing to ship, I need a new logic board for my 2.5 DP - I could shoot you an offer if you're interested.

 

[Certificate of Excellence]

Some guys over on Tinkerdifferent are using sonic tooth picks like This thing to get stubborn corrosion off pcbs & little components etc. and report great results.