Weird cpu failure

[japerapaper]

Hi guys, I'm hoping someone can point me in the right direction because im out of ideas.

I wanted to upgrade my macpro 4.1 to 5.1 by swapping the cpu's to 2 x5680's.

The upgrade went fine at first, but after 3 days it started freezing like 10 sec after boot.

I swapped every piece of hardware in the mac with something else but it wouldnt help, so i went back to the CPU's. Removed CPU B from socket B and all is fine, no freezes. Placed CPU B in Socket A, all is fine no freezing. Putting back in both cpu's: Bam, freeze within 10 sec, the mac wont recover from the freeze.

I thought it might be broken B socket so I just put back in the old CPU's, and all is fine.

I'm out of idea's... anyone?

 

[ColdCase]

Can the power supply or traces handle the additional CPU load of the two upgraded parts?

 

[japerapaper]

Standard is 980 Watt so that should be enough, stripped all the extra hardware and still the same problem..

 

[flowrider]

Can the power supply or traces handle the additional CPU load of the two upgraded parts?

Sure, my cMP 5,1 is loaded and running X5677s just fine. A lot of other members have upgraded with no issues. The OPs issue sounds like a bad CPU to me.

Lou

 

[japerapaper]

The thing is, If I run it on 1 CPU it runs fine, same story for both cpu's. Is there anything that can be faulty in a CPU that only shows up if they have to work together with another one?

 

[h9826790]

So, the symptoms is...
1) When both X5680 installed, computer freeze.
2) When only one X5680 installed, no matter which one, computer won't freeze.
3) When both old CPU installed. computer won't freeze.

Therefore...
From 1, we can tell something is wrong when both X5680 is installed.
From 2, we can tell both X5680 looks good individually.
From 3, we can tell the CPU tray itself looks good.

Hence...
The biggest possibilities is that the X5680 can't talk properly with the other X5680.

I only know very very little about CPU. Is this possible QPI link related? Or if the CPU connector is dirty /partial damage, and it only makes the connection between the X5680's become intermittent?

 

[flowrider]

The thing is, If I run it on 1 CPU it runs fine, same story for both cpu's. Is there anything that can be faulty in a CPU that only shows up if they have to work together with another one?

Guess, I misunderstood. Sorry! Check the markings on the new CPUs. Are they exactly the same? When it fails, are there any red lights on the logic board?

Lou

 

[japerapaper]

Guess, I misunderstood. Sorry! Check the markings on the new CPUs. Are they exactly the same? When it fails, are there any red lights on the logic board?

Lou

No problem! There isnt any code on the CPU's, they are delidded by someone else there mightve been something on the IHS.
[doublepost=1475488371][/doublepost]

So, the symptoms is...
1) When both X5680 installed, computer freeze.
2) When only one X5680 installed, no matter which one, computer won't freeze.
3) When both old CPU installed. computer won't freeze.

Therefore...
From 1, we can tell something is wrong when both X5680 is installed.
From 2, we can tell both X5680 looks good individually.
From 3, we can tell the CPU tray itself looks good.

Hence...
The biggest possibilities is that the X5680 can't talk properly with the other X5680.

I only know very very little about CPU. Is this possible QPI link related? Or if the CPU connector is dirty /partial damage, and it only makes the connection between the X5680's become intermittent?

All correct! Same for me, also QPI I know nothing about. No visual damage visible. Unfortunatly not an extra pair of 5680 lying around either.

 

[thornslack]

Have you checked your thermals? Is the one socket over heating?

 

[japerapaper]

Have you checked your thermals? Is the one socket over heating?

Yes ive checked! And no there not..

 

[pastrychef]

Are you sure the steppings of both CPUs were the same? Is it possible that you got engineering samples?

 

[japerapaper]

Oeh thats clever, but how would I check that! I think the coding was on the IHS, wich has been removed..

 

[pastrychef]

If you have Windows installed, I think the app called CPU-Z will show stepping.

 

[japerapaper]

If you have Windows installed, I think the app called CPU-Z will show stepping.

View attachment 662417

I dont think thats the actual stepping, I remember it being a much longer hex string

 

[997440]

I dont think thats the actual stepping, I remember it being a much longer hex string

I'm not sure what you're referring to but through Mac, CLI you can get CPU info, including stepping, using this --

sysctl -a | grep machdep.cpu

 

[ITguy2016]

It's likely one of the CPUs is bad and thus resulting in the inability to use it in a dual CPU configuration. Is it possible to exchange them for a different pair?