MP 1,1-5,1 CPU-B failure on MacPro 2009

[ZNDK]

I restarted Mac Pro 2009 as usual and after the startup sound, it stayed on black screen for a long time. At the end of the day, there is no startup sound.
I pursued the cause and found that it was a problem with CPU-B in the CPU tray. It seems that the Mac cannot boot if the CPU is installed in CPU-B. I could confirm that there is no problem on the CPU side, as the status remains the same no matter which CPU I change to.
I checked the CPU-B socket and found no damage, especially bent pins. I adjusted the tightening torque on the CPU-B heatsink, but no matter how I tried. I also replaced the memory, but still no improvement. Currently, only the CPU-A single CPU configuration is available for startup.

Can this be fixed?

 

[tsialex]

First thing, while everything can be repaired, the parts/service cost would be low enough to make it economically viable to even try? Can you find a technician capable of repairing that have access to the required equipment and parts?

Since a 2nd hand CPU tray can be bought for around $115 from parts brokers like DW and sometimes even less from eBay, the cost of the repair will make it not worth, even for something "simple" as a damaged CPU socket or a blown MOSFET controller.

I'd buy a working dual CPU Mac Pro locally instead of importing a dual CPU tray. When you add all the shipping/fees/taxes the cost will be similar, but you can use it a parts machine or even buy a single CPU CPU tray and make it work again.

 

[ZNDK]

I have recently given up on dual CPUs and run with a single CPU-A only. Still, I am starting to have the problem again: when I turn on the Mac and around 1/4 of the way through the progress bar on the Apple symbol, the fan starts spinning at full speed. I have no choice but to use Mac Fans Control to make adjustments. How many is the optimum fan speed?

I was using a single CPU and had my doubts. What difference is there between the performance of a single CPU in a dual CPU tray and a single CPU in a single CPU tray?

I am again looking for dual cpu trays. I think the anomaly has been happening since I switched to AMD Radeon RX Vega 56 8GB. I have had to replace the CPU tray twice since I changed to this because it broke. The last time it would energize but not boot. This time CPU-B side failure. Why is that?

 

[tsialex]

I have recently given up on dual CPUs and run with a single CPU-A only. Still, I am starting to have the problem again: when I turn on the Mac and around 1/4 of the way through the progress bar on the Apple symbol, the fan starts spinning at full speed.

This is the expected and intended SMC behavior, when the SMC fails to detected CPU-B, it ramp the fans as a fail-safe precaution.

What difference is there between the performance of a single CPU in a dual CPU tray and a single CPU in a single CPU tray?

Differently from most dual CPU servers of the same platform back in the day, where you could buy it with just one Xeon and buy the second one later, the dual CPU Mac Pros are not designed to work with just one Xeon, except when doing diagnostics. AFAIK no one tested this since is not an intended configuration with a dual CPU Mac Pro.

Single CPU trays are faster than dual CPU trays for some metrics, like memory access since for the single CPU tray the memory is local, while for the dual CPU tray the memory is interleaved via Intel QuickPath Interconnect (only one NUMA node with a dual CPU Mac Pro). Dual CPU tray memory access is more than 20% slower than a single CPU tray. You have access to more memory, but it's a slower memory.

For someone that doesn't need more than 6 cores or more than 64GB of RAM, single CPU Mac Pros will always be faster than a dual one.

This time CPU-B side failure. Why is that?

It's an almost 15 years old CPU tray, that was subject to constant thermal expansion and contraction, humidity, dust, oily residue from the pads degradation, corrosion, component failure from the end of expected useful life and etc. It's no surprise that is failing, nothing works forever. Even if it was a brand new NOS CPU tray, the capacitors would be having issues by now.

 

[haralds]

I am just going through this. I was upgrading CPUs and fumbled one of them. It dropped 1/2 in. and ruined the socket. I have a single CPU backup tray and put that in. I got a fully functional tray from a reliable vendor on eBay for $125.

BTW, the single CPU tray had a 2.6Ghz 4 Core Xeon. I plugged in a 3.0Ghz 6 core and it made a HUGE difference in responsiveness to my use case.

Having all 12 cores makes a HUGE difference in Xcdode compiles of large applictions.

 

[ZNDK]

Thanks everyone for the advice. I have since switched to a single processor tray and have been using it. I certainly feel the instantaneous speed is better. I am concerned that the CPU usage often stays at 100% for a long time.
Then the Mac started up erratically again. The startup sound is heard, the first apple mark progress bar is normal, and the Mac restarts during the second apple mark progress bar. This repeats several times and eventually it can boot up to the desktop. SMC reset or NVRAM reset has no effect at this time. Is this really the end of the life span in sight? or OpenCore?