When shopping for a PC power supply, don't look at the total power, but check the manual for the power that's available on the +12V wires. It is usually less. Also, when have a multi-voltage supply, like a regular PC PSU, and you only draw power from the 12V, the voltage may drop more than in an application where the 5V and 3.3V is also loaded. The H-CARDs don't mind if the voltage drops a bit, but you'll get increased current, and this stresses the PSU even more.
so which PSU can You recommend?
wanna be prepared before miners arrives
Well any PSU really that has 400W on 12V rail (to have some overhead), has 2 6-pin PCIe molex connectors, over 80% efficiency (gold or platinum).
High efficiency PSU supports high efficiency of the chip, modularity is a plus also, and not required, but helps to keep that classic ATX wire-mess away.
If you have several units on order, I think you should consider one of the bigger PSUs, so you can have 1 PSU supporting several units. I use OCZ 1250 ZX myself.
Also note: if you are going to use Foofighters case, the maximum depth dimension of your PSU should be no more than 185mm. (This should cover ~99% of what's out there on the market, 1250W OCZ ZX is 175mm deep).