I spend 2 night with my 3870's in CF right now... They scale nice, but overclocking in CF with rivatuner is quite a PITA.

I stopped @ 891 / 1332 with gave me 23202 @ '06
Max memspeed was 1366mhz with 800mhz on the core.... not bad at al.

I going to test the cards one by one tonight, i'll keep you guys updated