They've worked perfectly in every 939 board I've tried, from integrated everything cheapo microATX boards to glitzy OC boards. Never had a problem. Update your BIOS (you should anyway regardless) and download and install the AMD CPU driver.
AMD gets very upset with mobo mfrs claiming official Opteron support on a normal desktop board as it's marketed as a server CPU.
Same is true of Mobile/Turion support.
Fwiw as far as I know they run on every abit & every DFI though.