Ive been having this issue since ~October of 2021. I will be either doing nothing or doing something and without warning my computer will shut off and then restart. There is no BSOD or anything. Everything just goes black then it restarts. Ive had this happen when I just start up my computer, when im doing general browsing, when im in a game, or when I just leave my computer idle at the desktop. This happens so randomly and so infrequently that I do not have any way of documenting it. Just this past week it happened twice within an hour but before that nothing for a few weeks.
 
Im thinking that it could be a PSU issue however I dont really have anyway to be certain until I swap it out for another. Im wondering if anyone else here would has any experience with this sort of issue.    
Specs:
R5 3600
Asrock X570 Phantom Gaming 4
48gb GSkill Ripjaws V 3200mhz
EVGA GTX 1070 FTW2
EVGA 850 G5
 
Let me know if you want any additional info

 
So one thing that sticks out to me is that you are using an odd configuration of RAM (48gb of Ram).  That could be causing stability issues and unexpected crashes.  RAM typically comes in blocks of: 8/16/32/64 and shouldn't ever be mix and matched.  Typically you would buy a kit and only the RAM in the kit should be used together.   No extra RAM sticks added...
 
If you are using Three 16gb modules, try pulling one out.  Make sure you have the 2 remaining RAM in the correct DIMM slots too (should be slots A2 and B2).  Your computer will probably run better with 32GB ram vs the 48 too..
 
 
 

yaymz
 
So one thing that sticks out to me is that you are using an odd configuration of RAM (48gb of Ram).  That could be causing stability issues and unexpected crashes.  RAM typically comes in blocks of: 8/16/32/64 and shouldn't ever be mix and matched.  Typically you would buy a kit and only the RAM in the kit should be used together.   No extra RAM sticks added...
 
If you are using Three 16gb modules, try pulling one out.  Make sure you have the 2 remaining RAM in the correct DIMM slots too (should be slots A2 and B2).  Your computer will probably run better with 32GB ram vs the 48 too..
 
 
 

Im running 2x8 and 2x16. Theyre the same everything besides capacity. memtest86 reported no errors.

I added the 2x16 later on. Given the information you provided I myself am leaning towards it being a ram issue. Ive removed the 2x8 and will see if that resolves the issue (who knows how long I will have to wait). If it doesnt I may try 2x8 for a while.
 
As long as it is just a case of mismatched ram or not being verified on the motherboard then im fine with the random infrequent restarts. I dont want to spend the money on new ram and I use well over 16gb ram in many cases. At least I know it isnt an issue that will get progressively worse/ jeopardize the rest of my hardware.

rjohnson11
Disconnect any external USB devices such as printers, external DVD rom players, etc and see if the errors occur, should the ram solution not solve it.  

No external usb devices besides mouse and keyboard.

I recommend only running the 2x16 kit and disabling XMP.  See how it runs for a while.  Then work on a good memory overclock that is stable.
 
There are plenty of 3200 2x16 kits on G.Skill's QVL for your board:
 
https://www.gskill.com/co...peed%C2%A73200%20MT/s,

Psu or ram gets my vote.

Jomama22
I'm putting my money on one of three possible setting to try, all in bios:
1: Disable DF Cstates. This will be buried in the AMD CBS menu under NBIO (or use the search function of the motherboard)
2: Disable Global C-state Control. May also be buried I'm AMD CBS, search if possible
3: change Power Supply Idle Control to Typical current idle. Same as above.

You can try one, all or some combination of the 3. The last 2 usually prove to be the winners.

Ryzen specifically has odd issues with it's low power states in combination with some motherboards. This has been a known issue since the 1xxx series. More or less, a core coming out of a low power state wont get the voltage it needs and it grinds everything to a halt.

Try them, leave the PC idle, and report back how it goes.

It's doubtful to be ram as those crashes usually won't result in a full power down as this issue does.

I have implemented the changes you suggested in numbers 2 and 3.

Well I was in the middle of a zoom meeting and it happened on me again. I'll try disabling DF Cstates next.
 
Im not sure if ive detected a pattern in when it restarts. It seems like it happens twice or thrice in a very short period of time then doesnt happen again for a number of weeks.

So the issue occurs on 2x16, and 2x8?

T1E6X1
I havent used only 2x8 and I dont really think I will go back to 2x8. However it occurred with 32 and 48gb memory installed. It could be that the ram kit is faulty. I dont really know.

If it is faulty then you need to test it one by one