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N8oR

macrumors newbie
Original poster
Jun 19, 2021
8
1
Hey everyone. All of a sudden my 5,1 died. I can't get it started again and I've tried all the basic stuff like restting PRAM, SMC etc. Took out all the drives, graphics card and even changed the ram sticks around (also took them all out at one stage). The power light stays on and only blinks when i take the ram completely out.

Signs are pointing to the logic board being fried but I'm hoping it's something else. Can anyone pleeeeease suggest something i can try out. Thanks heaps.

I pressed the Diagnostics led to see if i can make sense of it but too much of a noob. The very bottom led flashes and the rest are constantly lit. (See photo)
 

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Forgot to mention i noticed the rear cpu was significantly warmer than the front one. Whats that all about?
 
It doesnt flash and i dont have another one to try with unfortunately
 
It doesnt flash and i dont have another one to try with unfortunately
You wrote: The very bottom led flashes and the rest are constantly lit. (See photo)


anyway, if youre not in the position to try another cpu board then buy a complete system to repair yours and sell the remains in parts. If you do well you can get your replacement part for free.
 
You wrote: The very bottom led flashes and the rest are constantly lit. (See photo)
My bad. I thought i read something about the yellow led. Actually the very bottom two leds dont even light up at all now.
 
Don't think I can afford to buy all this just to test out unfortunately
Best idea is to buy a complete tower , must be another 5,1, maybe a single processor, and troubleshoot with that. Then if it is the backplane you can still buy them on ebay or whatever. I have replaced 2 successfully so far, one for me and one for a customer's mac pro. I had 3 5,1s of my own at one point but now I just have two. Touch wood I have only ever had one of the spares fail and i didnt know its full history. I think someone overloading the backplane power by installing the wrong video card is part of the problem, at least thats my guess.
 
By any chance, does the red led towards the back of the computer, next to the ram slots, is meant to stay on or just flash once when the power is switched on, like it's doing now?
 
GAAAARGGHHH!!

 
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