Mac Pro restart issues

[paulpaul87]

Hello all,

I have an intermittent problem with restarting my Mac Pro, it tries to reboot but gets stuck before booting anything. No grey screen, just the sound of the super drive spinning up which repeats in a loop until I hold the power button down to do a cold shut down.

The red CPU FAIL leds blink (but do not stay on). Anyone have any idea what this could be?

It's weird because it doesn't happen everytime (though it is more often than not) and it only happens with either manual or automatic restart (after updates for example) and when the machine is running everything is fine. Temps are normal, all memory/CPU cores recognised.

I have tried everything that I can think of. Resetting the PRAM, SMC, resetting the machine on the logic board, resetting the SMC on the logic board, taken out RAM, only used stock apple RAM, tried different graphics cards, and a clean install. No luck.

Please help me

 

[OS6-OSX]

It will help if you list some specifics.
1. Which MP
2. Amount of ram
3. OS used

 

[paulpaul87]

sorry - very careless of me not to include my specs.

MacPro 1,1 (with firmware mod making it 2,1) - before mod, problem still present.

Xeon x5355s - have tried with x5150s, same result.

16GB RAM (8x2GB) - have tried all combinations, all the way down to 2GB.

GeForce 630GT & 7300GT - have tried both at the same time, both separately.

OS X 7.5 - have also tried 7.1

Bus Speed: 1.33 GHz

Boot ROM Version: MP11.005C.B08 - this has now been modified, but even
before the mod, the problem was present.

SMC Version: 1.7f10

 

[alphaod]

I had this issue for a very long time on my 2009 Mac Pro. So I basically stopped restarting it unless I absolutely needed to.

After the Apple Store replaced the motherboard my issue was resolved. I don't want to say that's the solution to your problem, but it was for mine.

 

[paulpaul87]

Yeah you're probably right, it would make sense if it was the logic board considering everything I've already tried. Did apple tell you specifically what was causing the problem on the board?

 

[paulpaul87]

Ok, so it would seem that when I have 2GB stock apple RAM installed, restarts work fine. If I have 4GB Apple RAM, restarts occasionally cause a problem. If I have 3rd party RAM, restarts really don't work. It seems it is quite clearly the RAM causing the problem. Either the RAM I have sucks, or there is a problem with the RAM daughter board(s), me thinks the former to be more accurate. Anyway, I am pretty relieved that it is not a PSU or Logic Board problem. Now if only the apple stock RAM wasn't so freakin' expensive...