Random Restarts when idle

[zheavy]

I leave my PC on sometimes overnight or when I am away from home for big downloads or uploads. I have noticed that when i check my PC, my PC had restarted.

I am sure it can't be an electric problem because I am plugged to an online UPS at all times.

My specs:

• Mobo: DH61WW
• CPU: I5 2500
• Ram: Kingston 2x4B
• SSD: Samsung evo 860 1TB (main drive)
• HDD: WD green 1TB
• GPU: Zotac GTX1070
• CPU: Thermeltake 630W Smart SE

I have never had the problem while working or during my PC usage and I've used it for extended periods in some cases. This has been happening for awhile, but I thought It could be restart from windows update or some softwares that I have left to update on it's own, but just last night i was trying to upload some large files and realized that my clients never got the files. I checked my PC and turns out it had restarted, i have tried twice over the past 2 days with same result.

 

How can i identify the issue here? could it be a software issue as well? is there some timer that I may have placed on my computer for idle without my attention?

 

Best Regards