It depends 'how' the PSU fails...

If it fails nicely, then changing the PSU will restore the unit to full operation.

If it fails badly, then various cards can be cooked! To a certain extent, it depends on the model.
I've seen a lot of tuner cards fail, and some FICL cards too.

The main issue with G-series is ventilation. If you leave them on 24/7, then they slowly overheat and cook the capacitors.
I've yet to see a G68 fan operate!

Good luck,

Steve