Question PC Restart when underload

[21vonLutjens]

I got a problem here, my PC rebooting when underload or gaming with no BSOD just suddent reboot and some PC Hang after screen went dark. IDK is that GPU problem or another thing. I just replace PSU to CV 750 watt from Corsair, also i always update driver and using DDU for updating driver, i did underclock to 2350 MHz and undervolt to 1100 MHz but still had the issue. IDK what should i do can you help me guys? Thanks a Lot

My PC Spec:
Ryzen 5 4500
Asus A320 MK
RX 6700 XT
16 Gb Ram DDR 4
Corsair CV 750 watt

i know my PC spec very inappropiate, i am suspecting the motherboard cause lasttime i am using RX 6600 its completly fine but when upgrade to 6700XT i got this problem. oh yeah its on stock no OC

 

[Nine Layer Nige]

Sudden shut offs are quite often due to a bad or unsufficient PSU. It may be a new PSU, but it could still be the problem.

 

[21vonLutjens]

Sudden shut offs are quite often due to a bad or unsufficient PSU. It may be a new PSU, but it could still be the problem.

I forgot to mention i just change my psu twice but still have this problem