OptiPlex 7460 All-In-One computers power issues

Hello all, I manage a classroom of 21 Optiplex 7460 AIO computers. They are on Windows 10, we patch the OS to the highest level a month or so after Windows is updated. 

What happens is the machines power down on their own, and can't be turned back on via the power button as you would expect. In order to power them back on, you have to pull the power cable from the rear, wait a moment, plug it back in and then the machines power on. 

This problem is not specific to any one machine, at any given time up to ten or so machines will power down. It isn't always the same machines, it happens over the course of a week, I cannot recreate the problem. 

Windows logs show a power down command as being entered, but this will happen when there is no one sitting at the machine. 

I have changed the BIOS settings to disable sleep, and to have the machines power on each day at 6 AM, and to resume power on state in case of interruption of power. 

These all in ones have Nvidia GeForce 1050 cards in them. 

I have used Dell Command|Update to bring all the drivers up to the most current version, including the BIOS. 

I am actually wondering if that was a mistake, since I erased a machine and installed only Windows 10 and whatever drivers that loaded, and so far this machine has not had that issue. 

Has anyone ever heard of something like this? I will probably reimage the machines and hope for the best that way, but any advice would be appreciated.