Continuous rebooting on FIRO and RVN mining

Hi I have a 2060 (non-super) on a old mobo and 330 watts PSU on HiveOS. I used to mine ETH about 2 months ago with 70 watts power usage and 30.9 Mhs with this OC: (core:1095 MHz , mem:1501 , PL:125w) but then, I decided to switch to RVN for some time but after finding my pc keeps rebooting every few hours with 130 watts , ~18 Mhs with this OC: (core:205 , mem:-150 , PL:130) but whenever I use to cleanup mobo and gpu the the reboots become less (normally 10-5 times a day) but yesterday I try Firo with the same oc as rvn the reboots become much more some times it reboots at starting of mining and some times after 5 minutes. although I reduced the Power limit to 125 and it works few minutes more and also reduced mem and core clock to 0 so it takes 15 minutes before first reboot.
so at all my question is what is the problem? I read about it that the sudden reboots could because of CPU temp (that is normal for mine) or PSU that I think its faulty ذbut something that’s stranger for me is that how is that possible that my card works almost fine on rvn but on Firo it doesn’t work with same power usage and oc?
the specification of PC:
MSI ventus 2060
Pentium G645
8Gb ram
330 watts 80Plus PSU but about 8 years old

RVN coin need more power and core to be mined… also remove PL settings if you have,and check OC (wattage)…