The strange thing for me is that the temp, activity, fan speed, clock and mem speed have all shown up just fine for the 2nd card on any previous Catalyst versions, including 10.1 which has been the most stable for me by far. Yet 10.2, the 2nd card appears to shut down. Really noticeable when you force the fan speed up and 15 seconds or so after closing the CCC window, the fan on the 2nd card quits and suddenly there is NO reading from it. Everything drops to zero, where there used to be numbers...higher than zero that is, for you smartasses
Still, one 5870 is plenty powerful.
Edit: I should mention that I haven't tried running any graphics intensive program with xfire to make sure it's not a bizarre power saving feature as mentioned by h2on0. Seems odd to me that I used to have normal idle readings, but 0 now.
Epiphany edit: Yep... I thought it was already pretty power bill friendly, but I guess shutting one card down is even more so.