Mac Pro 4.1->5.1 Issues

databaze

macrumors member
Original poster
Nov 21, 2011
51
8
Hi,
After a loong time (almost 2 years), I had some time today to try one more time to revive a Mac Pro 4.1 that I had to stash away since it died on me back in April 2017.

The original post was this: https://forums.macrumors.com/threads/mac-pro-4-1-upgraded-to-5-1-wont-boot.2041789/#post-24497568

I had to use it for work, and since there are no really good repair shops in my area, I just bought a 5,1 on ebay and kept on working away.
Today, as I was cleaning up my office, I decided to give it a world and see if I could find what in the hell was wrong with this Mac Pro.

I started by doing the usual things and nothing, but then I stumbled upon this post created a Year and a day after my original post:

https://forums.macrumors.com/threads/mac-pro-4-1-wont-boot.2115068/

The part that I decided to try was the:

1) Install CPU A only (the rear one)
2) Try to boot

If success, the Mac should boot with full fan speed. Then go to step 4
And it actually did what it should!!

After installing CPU B I was able to boot into the OS for the first time in almost two years!

Now, here is the weird part:

When I looked at the system report, it shows as 6 core instead of 12 and with a max of 64gb of ram.
I have 12 cores and 128gb of ram that were previously detected before it died.
The thing is, I thought: "well, maybe the firmware got messed up or something" but it does show as 5,1

Here is where I wonder if anyone has any ideas, I mean, if the CPU B was detected, and I see no red led marking it as bad, why do I see only 6 cores and the rest of the ram is not present?

Any further help is appreciated as always, I will try to remove CPU B again and re sit it to see if that makes any difference and update this post if it does. But like I said, I would assume that if the CPU B was bad, it would not boot at all, so what gives??
Anyway, thanks for reading and for any help that comes my way!
 

databaze

macrumors member
Original poster
Nov 21, 2011
51
8
I'm about to clean the heatsink/cpu and apply new thermal paste. Will report back.
 

databaze

macrumors member
Original poster
Nov 21, 2011
51
8
It was all about pressure! I got it working after applying more presure to the CPU with the heat-sink, not I have it working like new!!
 
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