@Vigil: buck regulator switches of at 145°C +/- 20°C
see page 39 of the pdf, the IRF will be very hot.
http://www.irf.com/product-info/datasheets/data/ir3895m.pdf

@nekonos:
see https://bitcointalk.org/index.php?topic=190731.msg2329781#msg2329781