Yeah Nvidia are saying recommended is 750W but surely that would have to be a good quality one with not only the power requirements but the quality of the power rails? And then factor in, like you say ones that are not brand new like your Seasonic psu and then factor in therefore a fair amount of issues with 3090 users yeah. Having a potential 350watts needed the quality of the power supply would surely affect it?
Let's hope mate.
Fingers crossed though my other 2 mates have the same issue!
Mate 1. - MSI 3080 Gaming X Trio - same PSU as me bought around the same time (2013) - hes also getting crashes
Mate 2. - 3090 FE (same as me) - EVGA SuperNova PSU - also getting crashes.
I thought I'd be fine with a 70A single rail PSU, but I guess the age of the PSU has meant the spikes are causing it to trip or something. Fingers crossed I will update here though as I think others are having issues too.