System Auto Restart

Problem:- System Auto Restart
Solution:- So many type of solution u can check.

Point no. 1st :-  Power board check.
Point no. 2nd :-Check power cable
Point no. 3rd :- SMPS is OK or not
                         How to check SMPS ?
                         Ans:- Remove SMPS from CPU, u can see 20 pin  or 24 pin connector 
       Like this:-   

Then short pin no. 14 and 15, if SMPS fan is working when u short pin, then your SMPS is ok.

Point no. 4th:- Check system RAM is proper fix or not. After that u can check our motherboard.