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macrumors newbie
Original poster
May 29, 2019
As the title says, I tried to upgrade my mid 2010 5.1 CPUs last night with these delidded 3.06 GHz X5675 processors here:

I thought I swapped out the CPU's properly with thermal paste application and heat sink placement/tightening but after I slid the CPU tray back in I was getting a steady red LED light from CPU A on the dual processor board. The fans on the computer are blasting including those on my shoddy graphics card (which I am replacing as well). I'm also not getting any type of video.

I consulted the technicians guide and decided to switch the CPUs and now I am getting a steady LED light from CPU B and CPU A gives a quick red flash after hitting the power button. But again, after it powers on I'm greeted by blasting fans and no video.
When I power down the computer on the LED diag it is showing me "OVTMP CPUB."

I've tried to do some adjusting on the heat sink but nothing seems to be working and I am still getting the red light from CPU B on the dual processor board. Again these are delidded CPUs so I've attempted every different level of tightness/looseness with the heatsinks and still nothing seems to be working.

What could I be doing wrong? Or are one of the CPUs I got just a dud considering when I switched them, the "OVTMP" diag followed it.

Alex Sanders74

macrumors 6502
Nov 26, 2013
Toronto, Canada
Try running one of the new CPUs alone in the CPU A slot. Fans will run full blast, but the computer will boot if it's installed correctly. Might help rule out which of the two new Processors is bad. If one works, test the second to see if it works in the A Slot.

If that works for both, there could be a bent pin on the B slot... Have a gander.

Have you looked at the rivets on the Northbridge heatsink at all? If they've popped, it can also cause this type of behaviour.


macrumors 68000
Dec 16, 2004
5.1 Mac Pro's use "LIDDED " Cpus just flip the clamp ! . . .much easier that the 4,1's DE-LIDDED cpus


macrumors newbie
Original poster
May 29, 2019
Big problem.

You should use the normal CPU. There is a 2.2mm difference in thickness. And without the lid, there is no way that the clip can secure the CPU in the right position (which provide proper pressure to the pins).

Oh wow, i should have done more research to make sure that mid 2010 NEED lidded processors. I'll report back if the lidded ones work and I don't have any problems.


macrumors 68030
Dec 27, 2015
I bet you have a 2009.

Does the sockets had a clamp ?

Lidded and delidded cpus look totally different. If you had really installed delidded than they made no physical contact to thr heat sinks.
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