The sm8/st10 pedestal is 284mm W x 197mm H x 568mm D
A 480 Monsta with p/p fans is 136mm tall. So it would fit in the pedestal. The same 480 Monsta in p/p fan config will fit in the bottom of the case, where there is 152mm of space. And it will fit in the case top, not the extended top, because there's 152mm of space.
Do your math before going off to buy rads ... when the ad copy says This package allows dual 480 radiators (up to 145mm thick)
- the 120mm extended top will house an 86mm thick rad with 1 set of fans, the 2nd set of fans being inside the case. So there is 120mm of space available in the extended top plus 25mm of space in the case, equalling upto 145mm of space.
Take a look at this pic - that's the ST10-x with a Monsta and 1 set of fans in the extended top area - though there are no fans in the case top, there's obviously plenty of room for a set.