I am not an engineer. As far as I understand they found a way to do some over-clocking combined with the bigger fan.
As soon as I test them I will provide screens. They push it to 420 - 430mh/s per board, so with 4 boards 1.7G is possible.
PS: Yeah, the ROI is always a problem since the beginning of this year ; )
The custom mining thread is full of posts about Spartan 6 LX150 FPGA boards, and I'm sure that if someone had managed to overclock them to that extent we'd have heard about. You're not dipping them in liquid nitrogen by any chance?
Seriously guys, due diligence here.
Some lancelots can actually do ~420 mhash, needs the latest firmware release by ngzhang, for those boards that can not perform at that rate, I guess some mod is needed. I saw many lancelots modded and that kinda ruins the board's good looking.
I think that what blackarrow is doing is making that mod a default setting combined with latest firmware.