SC Tom wrote:
Recently (within the last couple of months), I have been having
sporadic, spontaneous shutdowns or reboots. The PC is only about 18
months old, and I have made no changes to it in the last year or so.
When it shuts down, I can restart it without waiting; it starts up
fine and immediately.

I had a problem like that once and it was the result of an extra "pin"
in the case which didn't align with a hole in the motherboard. Someone
else on the Internet solved exactly the same problem with the same
case/MB combination so I ended up only had to slide some electrical tape
under the known problem spot of the MB to fix the problem (i.e. I didn't
have to remove the MB). Before I found my "fix" I was producing
"spurious results" by pressing down at various placed on the MB. You
might try that after you check out your power supply. Good luck!

BTW, I recall now that I had a similar problem in another computer
whenever Norton Antivirus woke up the computer to perform an "automatic
update". I ended up solving that problem by switching to a different AV
program. My only guess was that my (Corsair) 750W power supply caused
too much of a power surge?

Bill


There are no entries in the event log other than for unexpected shutdown.
Core Temp shows no unusually high temps; it has never logged anything
closer than 35°C to TjMax.
The inside and vents are clean- no cat hair or dust. The fans are all
clean and running well.
CHKDSK shows nothing wrong.
MEMTEST86+ returns no problems.

My specs a
Lenovo H50-55
AMD A10-7800 Radeon R7 (12 Compute Cores 4C+8G) 3.50 GHz
12GB Ram
2Tb C: drive (came with the PC)
1Tb D: drive (used for data and movies, etc.)
SATA DVD drive
Nvidia GeForce GTX 750 video card
Corsair CX Series 600 Watt 80 Plus Bronze Certified Modular Power
Supply (replaced the original 180W PSU to power the video card- wasn't
impressed with the GPU graphics)
Logitech M705 mouse
MS SideWinder X4 keyboard

Windows 10 Home x64 V.1709 (Build 16299.125)

I'm getting ready to tear it down and check for puffed-up caps on the
MB and PSU, give it an extreme cleaning, and pull the heatsink and
apply new paste (replaced it about a year ago). Will reseat all cards,
drive connectors, and memory sticks. Might as well replace the CMOS
battery while I have it apart.

Anything else I can check while I have it apart?

Thanks for any suggestions :-)