Possible, never tried. However they are essentially identical in design, I'd be extremely surprised if there was any temp difference at all assuming you could even use it. You should be able to screw on the extra NB fins from the REX in place of the stock 'pin fin' NB block.....not sure if this would help at all though the main issue is the crappy block & 3 layers of paste. The basic design is absolutely terrible for both HPA's.