i found the same question in the net and this is the transcript of their conversation:
'check the box in catalyst, it should blink then give you some message'
'go into overdrive, click the drop down arrow, if it allows you to overclock two cards separately, then cf is enabled in catalyst'
'now that we've determined cf being enabled, take it for a test drive'
here's the link to this conversation: url://hardforum.com/showthread.php?t=1252264
I hope it helps.