Re RiscPC cooling
I've done this mod on all of the RiscPC's I have owned.
On a two slice machine with only podules in the second slice and a PC card on the motherboard, I blanked off the cooling slots on the top slice thus forcing air out only via the slots in the bottom slice. The machine became more stable in hot weather as a result of these changes.
My A3010 used to crash a lot in summer when the ambient temp went above 25'C