2011 Mac Mini i7: reboots on wake from sleep

I've had my Mac Mini for just over 5 years, and it has developed a strange problem. It reboots itself when it wakes from sleep. It will then continue to reboot itself 3-5 times with a black screen, then it will boot with the gray screen and go to the desktop as normal. It will also do the strange rebooting procedure when powering it up.

For troubleshooting, I replaced my 16GB of memory with the original 4GB to see if that was the cause. The problem persisted. I then tried removing my 30" ACD, as I thought perhaps the mdp->dual link DVI adapter could be causing something. Still nothing.

I then tried a full reinstall. I wiped the disk and put a fresh and clean copy of Sierra on it. The problem is still there. I then pulled the 750GB HDD and replaced it with a 320GB one I had with Lion on it. I reinstalled Lion (the OS the Mini came with), and sure enough... it rebooted again on wake from sleep.

I've basically tried all new hardware that can be replaced, as well as fresh installs of the OS without any success. My question is, is there a BIOS/SMC flash for this thing? If something is corrupt, it might fix the issue. Otherwise, I'm looking at a logic board/processor replacement, and Applecare ended a couple of years ago. I'm not really in a financial position to be buying computers right now, so I'm in a bit of a crunch.

Thanks in advance!

 

Occasionally. In fact, last night it was just sitting idle, and BOOM. Reboot. It hasn't done that before (that I know of).

 

Yeah, it sounds like a hardware issue to me as well. I was hoping there was a bios/smc flash for it, but the only thing I've found is a security firmware update. I'll probably try it, as it can't hurt.

I've only opened the machine once in its entire life, and that was to upgrade the memory from 4GB to 16GB. If it was damaged, it wasn't because of anything I did. It's connected to a UPS, so a surge is unlikely, though not impossible.

 

That's an interesting idea. I'll give it a whirl. It definitely can't hurt!

 

Nope, no change. It doesn't matter where it's plugged in.

 

One thing I hadn't thought about was a possible power supply failure. This would make sense, as when it's trying to boot/start up from sleep, it acts like it wants to start working and then powers off to start again. It's possible that the power supply is starting to die.

I've got a new one on order ($20), so we'll see if that fixes the problem. If so, I'll report back here.

 

The new power supply arrived, and I've installed it. The machine still has the same issue. It's definitely something with the motherboard/processor. Oh, well.

On a lighter note, some friends of mine caught wind of my computer plight. Since we aren't in a position to replace it right now, they and some other friends set up a fund and purchased me a new 2014 Mac Mini 2.6Ghz to replace this one. I was truly humbled by their generosity. It's currently up and working flawlessly. It's surprisingly snappy, even with the 5400 RPM drive in it. Down the road, I'll pick up a PCIe SSD and set up a fusion drive on it.

 

This was such a frustrating problem, and no one had any answers at all. It's like it never happened to anyone but me. I'm sorry it's happened to you too, as these machines are still very viable today. Unfortunately, looking for the exact problem is like looking for a needle in a stack of needles. Basically, it just needs a new logic board.

I'm going to keep my eyes open for a new logic board for it, as it's a shame to waste the rest of it which works so flawlessly. Hopefully down the road I'll be able to do that.

 

I actually tried that, but when it's on for a long period of time, it just spontaneously reboots itself. That alone became an annoying factor in this whole saga.