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The Early 2009 Mac Pro—also known as the Mac Pro 4,1—introduced Intel's Nehalem architecture to Apple's line of professional desktop computers in March 2009. The Mac Pro 5,1 used the same interior design but received further CPU updates in 2010 and 2012.

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Kernel panic on startup after cpu upgrade

So, I was thinking of upgrading my early 2009 Mac Pro 4,1 Nehalem dual Quad-Core 2.26GHz to a Westmere 12-core but before getting my hands on such CPUs I thought I’d try out a couple of x5570 2.93GHz quad-cores (lidded, fitted with washers and 5mm thermal strips, I happened to have laying around.

The machine is firmware upgraded to 5,1.

I had to re-set cpu b about a million times before the computer would boot without any blinking power button or red lights on the backplane.

It boots fine with any of the two single processors on its own (with red light and fan at full throttle) but when both are installed I get kernel panic on startup.

I’ve reset SMC, started up with opt+R+P and nothing helps. It won’t boot in recovery mode either.

I’ve also removed the Northbridge heatsink and cleaned up the dried thermal paste and reapplied with new.

See linked picture of panic screen here: Kernel panic

(I don’t understand aaanything of it)

Any ideas?

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What system are you running and how was the firmware flashed?


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Im having the same problems. Mayer any ideas?

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Did you solve the problem? I've got the same trouble

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I gave up for a while, then I refitted the cpu’s 20 more times and then the kernel panics stopped. However one of the heatsink fans isn’t working and I can’t figure out why, maybe the board, maybe the heatsink fan itself. Good luck!

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how thick washers? I used 2 M4 (2.2mm) How tided screws?

Thats for beginning - I need to give MANY more specific informations - if not - no help :(

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i have also questions about problems with the cpus not detected,

the no-booting mac :-(

have to check if the processors are already working

have to check if no pins are bent on the socket under a cpu

i found that..

1) the black connectors of the heatsinkers ,

have to be reseated (a little bit out of their original position).

to be perfectly connected.

2) doing this tricky operation… NEVER OVERTIGHTEN the springscrews when seating back the sinkers.

cross pattern. never press on the top of the sinker.

count the number of rotations before (when removing the sinkers),

note them, and reproduce them with care

3) have to respect the difference of thickness of a delidded cpu and a lidded one. (3mm or 5mm),

this layer…. with 3 or 3 washers?

5mm thickness of thermal strip ? he removed the original pink layer.

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