Computer freezes randomly

First of all, no one other than you has any idea what motherboard you are running, what pw supply, etc. Post ALL of your exact system specs. Note 16gig of ram does not tell us much however 2x8 of corsair xxx123 would tell us a lot more.
Next have you checked your temps and voltages? If not do so. Most board mfg have purpose designed monitoring software on the support page however we have no idea what board you are using so that may or may not be an option.

 

OK, you are not understanding. You need to post the exact specs. You still have not posted the exact pw supply. Next this is a gigabyte board so go to the support page;
https://www.gigabyte.com/Motherboard/GA-970A-UD3P-rev-10#ov
Download and install easytune [in the utilities section] Once you have easytune installed and you have rebooted, post the following info; cpu temp, 12V, 5V, and 3.3V values. Do this twice; once under a normal load and once while running a stress test ie prime95 or OCCT. Let the stress test run for at least 2min to stabilize temps and voltages.

Note easytune is also an overclocking program. Do not make any changes; just monitor the hardware.

 

You have your answer; 87C is too hot. The system is overheating. While you may have other problems, you need to fix the overheating issue then go from there.
12V, 5V, and 3.3V rails are a little low however they are holding at the same value while running prime95 so that is probably not the problem however sharktoon pw supplies are junk and I would replace ASAP. That pw supply might be ok to run onboard video however in no way is it capable of running an amd 580.

In short, fix the overheating problem and install a quality pw supply.

 

Good ie recommended brands; corsair [AX HX, or RM models ONLY] Antec [HCG models ONLY] or Seasonic.

 

70C should be ok; a little warm however you have a 125W processor and those do get hot when stressed. Start testing other things, ram and hard drive. Use memtest to test the ram http://memtest.org/
Let memtest run for at least 1hr to see if you get any errors. You have a samsung ssd so if the samsung magician software says it is ok, it probably is fine.

 

It may simply be that your motherboard is failing. That board is now 6yrs old. If you want to continue troubleshooting, you are going to have to start swapping parts; ie ram, motherboard, hard drive, etc until you find what is causing the issue.
FWIW I would not invest money into 6yr old hardware however that is up to you.

If you want to do some more [no cost] troubleshooting, reseat the processor. While you have the processor OFF, clean the socket with some contact cleaner [available at any auto parts store or electrical supply store] Just a few very short bursts into the socket pins and let fully dry. Replace the cooler after you clean the cooler and cpu with 99% alcohol. Apply new thermal compound and install.
Reseat both atx and aux pw connectors on the motherboard. Inspect both the plug and socket for any burn marks or signs of arcing. Be sure they are fully seated.

The above will cost a few $ for thermal compound and contact cleaner however it is much cheaper than replacing the mb, processor, etc for more advanced troubleshooting.