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warmachine4pres

macrumors newbie
Original poster
May 3, 2015
4
0
Greetings,
This post might get lengthy as I want to be thorough in my explanation so I can get a proper diagnosis.
I recently bought a Mac pro 2008 3,1 (2x 2.8 GHz quad-core, 8gb ram, ati 2600xt) and it ran fine when I first booted it up (running osx 10.8 at the time). Although the computer was working, the previous owner let a lot of dust accumulate inside. I installed Yosemite on the machine then shut it off. After that, I took the computer apart for dusting. I dusted each part with an air compressor then I reapplied heat sink paste to the CPUs. After reassembly, I press the power button and the GPU fan starts spinning at full speed. There is no chime and the computer doesn't boot. I removed the graphics card and power on again. The front light doesn't blink, so the computer isn't recognizing that there is a problem. Next, I removed the ram, same thing, no blinking front light. I tried resetting the smc, checking the diagnostic LEDs (http://imgur.com/B55Jhlg) but nothing seems to work. I did as much research as I could and concluded that it's a logic board issue. I thought I'd ask here first before buying one though. So TL;DR Bought a working but dusty Mac pro, dusted it, and now it doesn't work and am wondering if I should buy a new logic board or not.
 
Last edited:

nigelbb

macrumors 65816
Dec 22, 2012
1,140
264
So TL;DR Bought a working but dusty Mac pro, dusted it, and now it doesn't work and am wondering if I should buy a new logic board or not.
You have done much much more than simply dusted it as you have removed the CPU heatsinks to apply new thermal paste. Did you remove the CPUs? have you bent any pins?
 

warmachine4pres

macrumors newbie
Original poster
May 3, 2015
4
0
Yes I removed the CPUs. I don't think I bent any pins because the diagnostic lights would say that it doesn't recognize the CPUs.
 

warmachine4pres

macrumors newbie
Original poster
May 3, 2015
4
0
I'm assuming that I either have a bad logic board or a bad PSU. I have no way to confirm either though.
 

rueyloon

macrumors regular
Sep 24, 2013
187
11
in case you are running extra drives using the internal "free" sata, don't. I had the same problem until I still using those ports and the computer is stable once again.
 

Draeconis

macrumors 6502a
May 6, 2008
985
280
Carefully reseat the CPU and heatsink, sounds like the Mac Pro isn't seeing the fan on the heatsink.
 

CLMNT

macrumors newbie
May 5, 2015
4
0
Hello,

The compressor has an air filter ?
There can be projections of water / oil and little cause short circuit.

My mac pro is also a bit dusty but I restrain myself to spend a compressor as didn't have filter
 

warmachine4pres

macrumors newbie
Original poster
May 3, 2015
4
0
Carefully reseat the CPU and heatsink, sounds like the Mac Pro isn't seeing the fan on the heatsink.

What makes you say that? It is only the GPU fan that spins at full speed. The other fans kick in about 5 seconds after power on, but they run a normal speed.
 
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