Computer shuts off randomly

[Bioxed]

My computer shuts of randomly. When it does it stay off for 5 seconds or so and then turns back on. It goes to the log in screen,I log in and the windows runs for 10seconds then poof shuts off.

Specs:
Mobo: asrock h67m
Ramatriot viper 8gb (which i replaced because I thought it was causing the issue)
Cpu:intel core i5 3450S
400w power supply (old)
Here are bios pics that might help:

 

[OlittoTV]

could be your cpu, with the pictures you provided i see your cpu temp is at 53 degrees Celsius just in the bios so when the cpu is maxed out the temp may goto 90-100 degrees Celsius that may be your problem to test if it is do your normal thing but monitor the temps in windows with a program like realtemp(search on google for download) and see how that goes. otherwise it could be a power supply or ram issue. as you say the power supply is old so borrow one from a friend or another pc (if possible) and the plug that in and see if that works and if you plan to buy a new psu go for a corsair or seasonic power supply

hope this helps!

 

[Bioxed]

could be your cpu, with the pictures you provided i see your cpu temp is at 53 degrees Celsius just in the bios so when the cpu is maxed out the temp may goto 90-100 degrees Celsius that may be your problem to test if it is do your normal thing but monitor the temps in windows with a program like realtemp(search on google for download) and see how that goes. otherwise it could be a power supply or ram issue. as you say the power supply is old so borrow one from a friend or another pc (if possible) and the plug that in and see if that works and if you plan to buy a new psu go for a corsair or seasonic power supply

hope this helps!

Yea I downloaded the programs that read cpu temps and i always got 50-60C not doing anything and then when I would run prime95 it would jump to 90C so I turned it off fast. I ran memtest that ran well but I hope prime95 didnt burn my cpu. Also the cpu shuts down while I work in Cinema 4D or play games...and then I get this problem that i cant have it turned on in windows and after I leave it few hours alone then it works. I guess the cpu cools it self after a few hours.

 

[OlittoTV]

you should try reseating your cpu cooler as the thermal paste may not have enough contact with the cooler its help and when reseating make sure to clen off the thermal paste and applying some fresh thermal paste, if you dont have any around buy some online for a few £s or $s.