Here is the original thread I posted about this heatsink. The first post shows the fan mounting and the heatsink mounted to the unused motor location.
http://www.rc-monster.com/forum/show...quark+heatsink
I used 5v fans, but many have used 12v running off the main packs.
I have done some experimenting with the fan setups since the original post and I found that I really don't really even need fans in most cases. The temps run a little higher without them but I still don't have any thermalling problems. The heatsink pulling the heat away from the bottom of the Quark case is enough from what I have found. Use some thermal compound between the Quark and the heatsink. This is what I like.
http://cgi.ebay.com/Arctic-Silver-5-...QQcmdZViewItem