I've had over-heating problems with my Rackbrute 6U, its getting sent back after a lengthy trouble shooting session with Arturia Support, it smelt like melting plastic, when i put the exact same module + more into my Tiptop Happy Ending Kit they all run cool. Real shame to be honest as it was about the prefect size / setup for the money and for my plans.
Bought it from Bax-shop in the UK, having real trouble getting them to send a return shipping label for it, they keep saying they have emailed it but nothing ever arrives.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.