Windows 10: PC shutting down / rebooting whenever i lock it

I have a surface laptop 3. Whenever i lock the device and walk away for more than 5 minutes, i come back to wake it up and it seems like it shuts down or reboots instead of just being locked. I've checked my power plan settings, i've checked my keyboard to make sure macros are not set up. The only thing that i can think of is possibly thermals but i see no evidence in logs that there were improper shutdowns. Is there any other cause that could be doing this? It's causing work stoppage because of data loss.

:)

 

PC Build Steps

Ok just because I like steps i am going to create some steps. Please give me the stamp of approval/disapproval

• Install system in case
  • Remember to connect SSD and optical to same SATA ports on motherboard
• Turn on PC
• setup HDD
• run blend test in prime95 for 30-60 min
  • run realtemp at the same time

• While in Prime95 test
  • if CPU goes above 70c in RealTemp, I have a leaky CPU
  • if my system locks up or blue screens, there is an instability in the system somewhere
  • if my system does not lock up or blue screen, my CPU is not damaged and I am in the clear!

What do you guys think??

 

PC Build Steps

1.1 - Ideally put optical in SATA 0, and SSD in SATA 1, this will cause the optical drive to be the default 1st boot option. You can change it manually if not, but I like it this way
2.infinity - yes, that's fine. if it's above 70 +/- 5 degrees, then it may just need a repaste/remount

 

PC reboots (no BSOD) on CPU stress

Hi fellow TPU members,

not too long ago, the box my gf's PC was transported in gave way on the stairs. Yes, you got it right, that sent a PC tumbling down a flight of steps alright.

Stuff broke. Also, stuff remained intact somehow.

I bought her a new case, new CPU cooler and we removed the floppy drive, so far so good. But the PC started crashing for no apparent reason, without a BSOD.

I tested:

• Memtest86+, left overnight, 0 errors
• Scanned the HDD for errors, nothing there
• Left FurMark burning up the GFX card and drawing some power, no problems there
• Ran Ubuntu from a Live CD doing nothing special, didn't crash
• Ran OCCT, Linpack, Prime95, all 3 caused reboots within minutes
• Oh, and I disabled "Restart on error" so I'm sure it's not a BSOD.

Now, I can still try and test something CPU intensive on Ubuntu, but my guess is the CPU didn't survive.
Before I do anything drastic like whippin' out the magic wallet and get her a new AMD quad, is there anything I didn't see?
I'm guessing the motherboard could be borkered as well, but can I check that other than replacing the CPU with a working one?
Any suggestions on which proggies I can use from an Ubuntu Live CD to stress the CPU?