BF /w 16x H-cards in Spotswood rack: 374 GH/s @ 256W
[img ]http://i.imgur.com/dpxX3yb.jpg[/img]
Bitfury. 240 Gh/s. 500 W.
[IMG ]http://i.imgur.com/gBac5R6.jpg[/img]
I highly doubt your BF boards are pulling 500W. And ya, you can't cool 500W with a few passive heatsinks like that.