Just drill alot of vent holes in to the PSU casing to get some air flow as hot air tends to rise.
Look at the picture of the watercooled PSU over at
http://www.zerofanzone.co.uk
http://www.zerofanzone.co.uk/picture...su/psu_032.jpg
Great job by the way, TimeLord!
EDIT: using the [img.. thingy wasnt a good idea with such a big pic.