A few 5770's may work with the ACD, but don't waste your money on them, buy a 6870.
Some claim to have the "Batmobile" 5770 working with the ACD using a DP -> mini DP adapter. Well I purchased the cable and it doesn't work. If you are not using a ACD the "Batmobile" is a great card. I've PM injectx (the keeper of the infamous working/nonworking graphic cards with ACD list) and also PM the persons that claim to have the "Batmobile" working with the ACD, none have responded.
No bashing intended for Injectx....I just wanted him to update his list for working/nonworking cards. In fact, maybe the list should included any special instructions needed to get the cards working.
Back to the point, I just replaced my "Batmobile" with a XFX HD-687A-ZDFC. The card actually displays BIOS POST sequence...no funny stuff needed, you don't have to unplug and replug it to get it working. As you can see in the attachment I don't have the framebuffer set up correctly yet, but you can see it does support multiple monitors. It is dead quiet!
More to come." ACD & XFX HD-687A-ZDFC.tiff