On Sun, 14 Mar 2021 16:27:40 -0400, Larc
wrote:

Symptoms: started rebooting occasionally, progressively increasing with prior mouse
pointer fadeout or freeze (cordless and corded mouse) - stopped seeing USB wifi
adapter, although USB drives would still work - now won't post at all (power comes on
and case PLED and fans run for about 20 seconds, then reboot, rinse and repeat) - no
HDD LED - no signal to wake monitor - power to DVD burner on. Multiple reconnections
and even reseating of the CPU and heatsink/fan and trying different memory modules
didn't help.

PSU: Tested thoroughly with comprehensive digital PSU tester and everything 100%

Is there anything else I should check out? I'd like to learn it's not the
motherboard since a replacement that could accommodate the 7th generation i3 CPU in
it would cost about as much as a new 300 series board and i3-9100 CPU combined.

I'm not running a higher powered setup here since this isn't a main system, but one I
use for Windows Insider development testing.

Motherboard: ASRock Fatal1ty H270 Performance
PSU: Corsair CX500M

Regardless, I might throw a fresh PS at it before offhand writing it
off. (Once had an old (early Pentium, maybe dualcore) ASUS MB that
became quirky to intolerable. I kept it running on the quirky side by
tossing it fresh power supplies every couple of years. Eventually
beyond old won out and happened over quirky and squeezing pennies from
something that probably lasted me five years. In that case it was one
where an inexpensive PS replacements were as good, evidently, than
anything more serious. Back in the days. . .a PS is likely now the
more expensive proposition.)