1. I want to replace the 650W PSU with an 850W PSU, I wonder if someone could recommend one I could buy today to replace it?
The Corsair AX860i is probably one of the best 850W PSUs that can fit into a Batch 1 Avalon without any modifications.
Thanks that what I was thinking of getting.
I fitted the same PSU, runs them very well. As for the screws, you'll find there's a technique to it after a while (put the screw through hole first, then carefully slide the nut under and quickly use the screw to pin the nut to stop it from falling in. Screw and unscrew a tiny tiny amount to make sure you found the start of the thread properly, then align the notches of the nut with the edge they slot into. Push the nut up so the notches engage with the edge, pushing the superficially engaged screw up out of it's hole again. Then you can use the allen key to tighten up while holding the nut in it's correct placement)