Mac Pro randomly shutting down

I haven't tried rebuilding the Spotlight index yet. After watching Activity Monitor, it looks like runaway processes is a bigger issue than I originally thought, and this issue was pointed out earlier in this thread. The machine tends to shut off when a process (or multiple processes) goes over 100% CPU usage. We've noted some specific ones that are doing this:

• photoanalysisd
• photolibraryd
• mdsync
• lsd
• tccd
• mds

And there may be other ones hogging resources. I guess the next question would be why these processes are using up so much CPU, and how to fix that. The computer is shutting itself off more frequently now, so it seems like this is an issue that may be gradually getting worse.

So the steps are:

1. Run "sudo trimforce enable" in Terminal while running normally
2. Restart into Safe Mode to automatically clear the backlog on the boot SSD drive
3. Run First Aid on any other SSD drives

Does booting into Safe Mode require an Mac BIOS-flashed graphics card? Trying to boot into Safe Mode from a restart or cold boot just leads to the computer hanging on a black screen, the same thing that happens when trying to use Startup Manager (holding the Option key) with the current GPU. If there's no other painless way to get into Safe Mode, I have another Mac Pro with a Metal-compatible Mac BIOS flashed GPU that I could temporarily donate to this machine (or just put the hard drives from the problematic Mac Pro into the working Mac Pro) for the sake of troubleshooting, if that would work and make things easier. Not being able to access most startup options due to the lack of the Mac BIOS on the GPU has been a recurring obstacle while trying to troubleshoot this computer.

After watching the computer more closely, it actually shuts off as soon as it sleeps, not shortly after. It's almost as if it's being told to shut down normally whenever it goes to sleep, because it doesn't give any error messages upon startup or show up as a crash or panic in EtreCheck.

It's also gone back to shutting off seemingly at random, not long after putting the USB 3.0 PCI-E card back in, and it continues to do this after taking the USB card back out. I'm not sure if it's a coincidence, or if this card is somehow messing up the computer. We've been trying to make a full backup to an empty FireWire Time Machine drive just for safe keeping, but it's been shutting off before it could complete it.

The computer has Temperature Gauge, and it doesn't show any alarming temperatures or fan RPMs while the computer is running. I've attached a screenshot from TG shortly after booting up the computer, if it helps any.

If you still think it might be a temperature issue, I can try monitoring it while doing things like trying to make a backup or whatever else.

I'm willing to try doing an NVRAM and SMC reset, but I want to ask about something else first, since it was recently brought to my attention.

Might the firmware have anything to do with the machine randomly shutting off and shutting off instead of sleeping? I'm aware that on the 2010 and 2012 Mac Pro models, you have to be more careful about making sure the machine has the correct firmware version when updating to Mojave, since the firmware isn't bundled with the OS and has to be installed separately. By any chance, can you tell me or point me to a source that can tell me what firmware version a mid-2012 Mac Pro should have when running Mojave 10.14.6? I'm guessing this comprises the "Boot ROM version" and "SMC Version (system)" attributes. The computer's System Information>Hardware Overview is listing Boot ROM version as "144.0.0.0.0" and SMC Version as "1.39f11" for both system and processor tray.

Might a launch service have something to do with processes (like lsd) going haywire and hogging CPU? I found another forum thread that gives a command to reset the Launch Services database in the event of it being corrupted.

We enabled SSD TRIM and ran First Aid on the non-boot SSD drive.

So, out of curiosity, we tried a little experiment in hopes of seeing if this is a software or hardware issue.

We swapped out the boot SSD drive running Mojave for the computer's previous boot drive that we kept- a spinning disk drive running High Sierra 10.13.6. We put the previous boot drive in the same drive bay in the machine as the SSD boot drive. We kept the two other internal hard drives that are being used to store photos and music. We also put in the computer's previous GPU, the ATI Radeon 5770 that the computer was manufactured with, effectively trying to "regress" the computer to how it was before upgrading to Mojave. The computer's owner doesn't really care for Mojave and would like to downgrade to High Sierra anyway, so we may trying keeping HS if possible. Any wanted documents and files are backed up elsewhere. The previous boot drive exhibited no hardware or software issues that would cause the machine to shut off. The only thing "mismatched" perhaps about this configuration now is the firmware, since it's still using 144.0.0.0.0. We're not sure if it's possible to install the appropriate MP51 firmware for High Sierra 10.13.6 for a mid-2012 Mac Pro. I know Apple has a page providing downloads for firmware versions prior to Mojave, if the one listed for the Mid-2010 Mac Pro model would work.

The computer seemed to boot up normally and run fine without any error messages. Not long after booting, the computer shut itself off, and it continues to shut itself off with no clear pattern like it's been doing. Nothing was spiking in CPU usage - the highest I ever saw was one process using around 40% shortly after startup. This leads me to suspect that it's a hardware issue, or possibly the firmware (though I would think it just wouldn't boot if the firmware was incompatible), since the computer was running fine when it had High Sierra and whatever software was on the machine at the time. We could try downloading and installing an older firmware version from Apple, but I'm unsure about that, with the computer shutting itself off still. I'd hate to see what would happen if it shuts off during a firmware installation.

Even with the original Mac BIOS GPU installed, I still can't get the computer to run Apple Hardware Test. I've tried holding D and Option-D during startup, but it doesn't do anything and just boots normally. I'm guessing that over the years of using the computer and swapping out drives and components, the AHT tools might have been lost. I've read about cases of that happening.

I managed to get the AHT version for the computer onto a bootable USB stick and ran it. A regular test didn't find anything. I'm going to try running an extended test, but I'm not sure if the computer will stay on long enough for it to finish.

An extended test came back clean, so I guess the RAM is good. AHT didn't give us any error codes, so I guess that means the issue is on the OS/software side, or it's a hardware issue that AHT just couldn't see.

We're putting the newer SSD boot drive with Mojave and the Radeon RX560 GPU back in, since swapping boot drives didn't help the shutdown issue, and apparently the computer was running rather slowly with the previous mechanical boot drive back in. The older drive may be failing, I'm not sure.

At this point, we're out of ideas and about at the end of our ropes. The owner is almost ready to just replace the computer, with either another refurbished Mac Pro or a Mac Mini. If it's a sneaky hardware problem, we can't find it, and can't afford to just repeatedly throw new components at it and see if that fixes it.

The situation overall hasn't really gotten any better since we started troubleshooting. It still can't sleep without immediately shutting off, and it still shuts off while running without any clear pattern, crash/error message, anything that points to a specific cause. It seems to run just fine when not doing anything, but when you try to do something on it, it's prone to shutting down, some noted examples being doing a large Time Machine backup or large file transfer via Finder.

Any other suggestions?

We didn't notice anything off on the processor tray. But I think we've figured out and solved the issue.

Just as a shot in the dark, we tried replacing the Mac Pro's power supply yesterday. Since then, it's been able to sleep just fine and hasn't had any random shutdowns. It even made it through a >1TB Time Machine backup and other tasks that would cause it to crap out before. And it seems to be running faster than before as well.

We're curious to see if we can check the output of the replaced power supply just to see if it's weaker than it should be, but as far as the shutdown issue is concerned, I think it's resolved.

So is there not any other way to run tests on the hardware besides third-party things like EtreCheck? Is the only option now to just tinker with the hardware to see if we can find a culprit?

I'm actually looking into that now after finding out about that repo from a stackexchange thread on AHT, haha. I'll see if I can run AHT from a USB stick and see if it gives us any leads.

Thank you to everyone who chimed in with ideas and suggestions!