My Windows shuts down unexpectedly

Hi,i have a big problem with my laptop.After i replaced its motherboard which i bought it from China online,my laptop closes every 2 hours,but without like shutting down on the screen or anything,it just turns off.The guy who replaced the motherboard didn't installed a new windows after,he just replaced it and gave it to me like that.Another thing is that aparrently my hard drive is on 26% health,maybe this could be a reason? but before the new motherboard everything was fine.And now please i need some help because it drives me crazy every 2 hours :).And everytime is 2 hours,like it has a timer or something inside and knows when those 2 hours passed.I'm thinking to buy a new hard drive to replace this one,to install a new windows and i'll see after.So any suggestions would help.Thank u

yes it is the right one because i checked the serial number and everything.i have a dell xps L501x,and this is the motherboard that i bought Wholesale Product Snapshot Product name is Original motherboard for XPS L501 L501x Laptop DAGM6BMB8F0 Intel HM57 0C9RHD C9RHD Full Tested Good Quality

If you are installing new motherboard it helps to reinstall all the installed drivers