Computer left on over night, bios reports:
CPU: 35 °C
M/B: 24 °C
CPU Vcore: 1.312 V
+12 V: 12.302 V
+5 V: 4.944 V
+3.3 V: 3.392 V
My measurements with two different multimeters:
+12 V: 12.29 V
+5 V: 4.937 V
+3.3 V: 3.384 V
Coin Cell removed: 3.060 V
I've sort of resigned myself to the boot problem- might get another new motherboard next year, but for now it is not a big issue in that I use my desktop 12 hours a day, and usually just leave it running 24/7. I normally go a week or two between hard boots anyway. Pressing F9, then F10 in bios gets me fully booted every time. I'm just too lazy to go through the return/exchange process for a replacement MB right now because the mouse/kb freeze problem is way more irritating.
My recent computer upgrade was motivated out of frustration with the mouse lockup problem. That 4 note sound when you plug or unplug a mouse or keyboard starts happening randomly after awhile and a lockup usually follows shortly after I start hearing that sound. Moving the mouse to another USB port, like to the front panel, or to another rear panel port, will bring back the mouse, but eventually even moving to another USB port does not cure the lockup, and requires a re-boot. It happens with the keyboard as well, just less frequently due to my surfing habits. Seems to me to act just like a buffer over-run, but of course I am only guessing about that.
It is hard to see how a video card could relate to this issue, so I will now assume that it must be software related. Although a fresh re-install of Windows 10 on my old system, including an upgrade from HD drive to SSD, did not cure the problem, I am facing what seems like the only possibility remaining- that some software 'somewhere' is the culprit, whether it is inadvertently or intentionally causing a mouse/kb buffer over-flow.
I thank you ever so much for your help, Cycloid. I will just put up with this issue for a little while. I am old and tired, but I will eventually reinstall Win10 again, but this time onto a newly formatted drive, eliminating the possibility of the malfunctioning software hitching a free ride. Take care,
mogur