Blizzie The heatsinks on the motherboard should all come off. Jacob didn't want them removed because.. well, why would you want to remove a heatsink. It's there to dissipate heat. If you swap all the sinks with waterblocks an give it a third party cooling it will be okay.
ESOOGYERG Using slots 2 and 5 in SLI is perfectly fine, And you'd easily be able to sneak a barb just below the first card even with an air cooler and still clear the card in slot 5.