Very nice X-Box box mod.
Should flip that radiator fan over so it pulls the warmed air out instead of pushing it down into the case like the original ATX power supply fans did.
Whenever I'd get one of those early ATX PCs in my shop, the first thing I'd do after evicting the dust bunnies was flip the fan and seal the internal openings on the power supply with aluminum tape so air would be blown up through the power supply and out the back instead of drawing cool outside air through the supply then trying to "cool" a hot CPU by blowing warm air in its general direction. Making the air go the right direction would cut the internal temp at least 10 degrees F and the CPU would run cooler.
Blowing warm air down into a case is also fighting natural convection. It's more efficient to assist the warm air to move up. You also never want more fan blowing into a case than drawing out. Either have the same flow or slightly more out than in.