Next: The PSU.
Choose a Enermax Coolergiant 600W PSU. This is for the whopping 600W and also for Enermax's excellent showing in the THG Torture Testing. However a regular PC PSU is too wide/high to fit in the base of the case where I intended it to go. It would hit the RAM and having a hot PSU against my potentially overclocked RAM is NOT a good idea...
Option is to put the PSU towards the front of the case but that would mean that it would be blowing hot air into the case. While I intend to make a acrylic divider that would isolate the lowest 'hot' compartment from the rest of the case, in reality, hot air rises. This would warm up the whole case.
As Sniper suggested, it was time for a total rethink:
And time to completely void the Enermax 5-year warranty. Oh well....
The layout of the Enermax Coolergiant 600W is very good, with a beefy heatsink and components all well laid out for maximal airflow.


However, it can be improved...
The plan is to make the PSU long rather than wide, with the on off switch at the top to facilitate switching on and off from within the case (I want to avoid cutting the G5 back if I can). The fan control knob will also be mounted at the top.
THIS is how I want the PSU to sit within the case...

And to do this, I'll need to make a custom acrylic enclosure:



Since I've already voided the warranty, might as well cut off the unnecessary wires too...

Have not decided how to put the acrylic together... Glue? Screws? I've got the glue ready, SuperGlue is NOT a good idea as it will discolor the acrylic at the point of contact. Have tested the Selleys MultiGrip Contact Adhesive and while it takes longer to set, it provides a strong bond and will not discolor the acrylic.