I've 3 of these

That's what we want... 

3 x 5850 (sapphire xtreme) under Linuxcoin. It freezes sometimes so I OC them just a little:

- Core: 750Mhz
- Mem: 250Mhz

I can OC one or two of them, but not all at the same time (freezes)... Maybe a PSU problem? It's the Corsair TX850.

A total of 900Mhash/s. Temps are ok (62-67ºC, fan in auto), I set the voltage to 0.95 and seems more stable. More parts:
- Mainboard Asrock extreme3 870
- Sempron 140

A power-meter says 345w at AC power plug.

I'm a new miner. I've 3x5850 in a Linuxcoin rig (that crashes sometimes) and I hope it get paid for itself at least 

No sabría decir, pero la verdad es que 2000$ me parece desorbitado.