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Jasper6120

macrumors newbie
Original poster
Feb 20, 2015
10
0
Hey Mac friends.
I'm in a bind here and I really need some assistance with a bricked 2009 Mac Pro 4,1.
I purchased this mac about 2 weeks ago. Its been working quite fine for the most part. Occasionally it would get a little glitchy, freezing up, taking a minute or so to open the finder window, and fans running full speed for no reason, but nothing that a PRAM, SMC reset or running cleanmymac wouldn't resolve.
The other night I was running a flight sim and I noticed that the graphics were a lot slower than usual. They were find rendering water and the plane itself, but would run extremely slow when rendering multiple planes in the far distance. This struck me as odd, because I didn't imagine this would load up the GPU much. Maybe the CPU though? Hmm.
Anyway, the next day I tried to turn my Mac on and it went into a boot loop. Chiming every minute or so, turning off and going again. I took the whole thing apart. Checked all power connections with a multimeter, reseated everything, PRAM, VRAM, SMC, External Boot Drive, nothing changed changed the boot loop at all. I then decided to remove the CPUs and found this (pictured below) as you can see, the temp sensor wires have been sandwiched between the washer and the heat sink. The internal wires aren't broken, but it could have caused a possible short or a malfunction of the CPU by uneven seating, poor heat disbursement. The needle contacts in the tray are cosmetically fine, there are no burn marks, but upon repairing the wires and reinstalling I still have not been able to fix the problem. I don't have any spare CPUs to test it with. I would love to hear some ideas on how to fix this!
Mac Pro CPU.jpg
 

Wando64

macrumors 68020
Jul 11, 2013
2,342
3,117
I could we wrong, but in my experience hardware either works or it doesn’t.

Sudden performance issues are more likely caused by software.
 

h9826790

macrumors P6
Apr 3, 2014
16,656
8,587
Hong Kong
If the heatsink temperature / fan sensor works, then I don't think it's the root cause of your issue. especially if you already put the wires back to the original position.

Anyway, you don't need spare CPU to test it. You already have two identical CPU on your cMP.

Just install CPU A only (with heatsink on, of course), then you can boot your cMP (expect full fan speed, that's normal).

If OK, then swap another CPU into socket A and see if it can boot. If yes, then both CPU and socket A are working.
 
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