Your computer stopped working unexpectedly.
Your computer stopped working unexpectedly.
So: 1) you’re not seeing a blue screen, 2) you need to turn the power supply on and off again before the PC starts up, and 3) this only occurs during games, not other programs. That seems like a power supply problem to me. Is your PSU still covered by warranty?
It's clear it's time to swap out the power supply unit. A fast online search reveals this model has been around for at least fifteen years.
The PSU isn't strong enough for the RTX 3070's power surges. You'll need a solid 500-650W unit. Look at the options and pick the best-rated model from the PSU Cultist rankings.