Wow 70 cards is a good haul! How many GH are you getting from those if you dont mind me asking?
Just north of 50,000 kh/s for Scrypt, with some more coming this week to put me at 60,000.
It won't last, but I'm glad I did this while everyone was focused on the ASIC race (I also ordered a 162Gh/s that won't make ROI most likely once it arrives). I also had a heck of a time with heat, but thanks to many hydroponics websites, they had a lot of information on cooling spaces. Those fans I installed with intake/exhaust, saved me about 6 tons of cooling. And after late september, the space will be under 80 degrees until May with just outside air being pumped in and hot air being exhausted.