PC Crashes, monitor and mouse and keyboard shut off, but PC stays on. (Need to hard reset afterwards)

[intrepid0183]

Hello, since i have built my pc, I keep having this problem where my pc crashes and the monitor goes totally black (stops getting signal from pc), mouse and keyboard shuts off, but the cpu fan, psu fan, gpu fans and case fans keep running. Each time this happens i hear a sound coming from the pc but I dont think it´s a motherboard beep (even if it is, its only one). After the crash everything boots up normally zero problems, but the crashes are more frequent. If i use my PC for 3 hours and it crashes, it will happen again but in a shorter amount of time. I have no idea why, but it happens. It crashes when playing a game or watching youtube and doing normal browsing.

I have tried using another RAM, I have freshly installed windows 10 multiple times, i have a backup power supply so I dont think its my power source. I havent tried replacing any other components since then, so I dont know if its my PSU or something else.
SPECS:
-Ryzen 1200 (not overclocked)
-GTX 1050ti Asus Dual (not overclocked)
-8GB of Crucial RAM
-1TB WD Blue
-AsRock AB350M-Pro4 motherboard
-EVGA 500W 80+ (normal one, not bronze)

I have been searching for a solution for a long time and have not found it yet, so if you can help me in any way, it will be much appreciated. Thank You!

 

[flarenial]

This sounds as if it could possibly be a heat problem. Check your temperatures and fan curves

 

[intrepid0183]

This sounds as if it could possibly be a heat problem. Check your temperatures and fan curves

I dont think they are, I replaced my cpus thermal paste recently and i use HardwareMonitor to check on temperature, i keep less than 70 while playing games on the cpu and less than 60 on the GPU. I keep all of my fans on full speed always, but I will check if that is the problem again thank you!

 

[seamus_ar]

I suspect the power supply may either be too small for your system, or failing, or both.