Hi there. I can happily report that I successfully upgraded my ROG G20aj with a RTX 3060 Ti founders edition.
I guess it’s the maximum you can upgrade in the G20aj in terms of power consumption for your PSU.
It works like a charm, very silent (fans turn off when idle), very reasonable in terms of power consumption (200w), fits like a glove in the case (though cable management is a pain)… So far, I’m very happy with it. As it is not a blower style card, I made some holes in the side of the case, for extra caution. Doesn’t seem to be a problem so far. I also changed the thermal paste during the operation.
I didn’t change the original PSU (apparently it’s useless with the G20aj which cannot handle more power anyway), just using the regular 180 + 230 power bricks.
No troubles with mouse or keyboard not recognised at startup (I made some changes in the bios thanks to spartan_hoplite advices), and no trouble with the drivers either… Card was recognised almost immediately.
I can now run RDR2 at high/ultra-settings in full HD with DLSS on with solid 60 fps (far enough for me and my video projector). Not too bad for a 2015 rig (7 years old !). I have yet to try Elden Ring… I’m probably bottlenecked by the CPU but I don’t really care to be honest.
If you need more info, don’t hesitate.