I have the same issues with 3870 cards which are modded. Today I will try going to a pure stock Diamond 010.073.000.xxxxx BIOS, no mods at all, to see if Catalyst 8.7, 8.8 or 8.9 recognizes 4 cards. Then if the BIOS voltage setting is what's really messing things up I will adjust my pots. Currently the cards run 1.4V idle, close to 1.7V at load. Remember these are 3870s. If I can get that working then I will try putting in the "Method #1" signature to unlock the upper speed so I can run the cards at 1000/1275. I'll post my findings tonight, hopefully. Same thing should apply to the 4850 too.