ztex,

I bought your 1.15d card and the power supply module on the internet a couple of months ago.  I was trying to get my own bitcoin miner working, but had some problems since my hardware background isn't quite good enough.  (I write linux software drivers for Android for a living, so I have good low-level software experience but not much experience with Verilog.)  However, I downloaded your design and it is working great.  I'm getting about 150-160 MH/s out of the Spartan6 LX150.

The obvious problem is that it gets too hot.  When I first power it on it can do about 190 MHz, but as it heats up it starts dropping frequency until it gets down to 168 MHz.  The passive heatsink you supply just isn't enough for this application. It's super-hot to the touch.  Can you recommend a fansink that will work well with the 1.15d board to keep it cooler?

Thanks.