FCPX playback problems

What are you making them with the Sony transcoder software?

I had the same problem (audio not sync, dropped frames, playhead random moves, etc) on a brand new 27" iMac, 3.1 Ghz processor with 4 Gb Ram. I upgraded to 16Gb Ram and now it runs like a dream. Everything is perfect !!

I think FCPX is RAM hungry.

The files were converted using Sony 'EXDCAM transfer' software version 2.5.1 I notice now the software version is at 2.12 may be that has something to do with it?

Apart from testing it to help Claudiu Im not really using the EXDCAM footage myself so didn't need to update the sony software, I haven't got the Sony EX1 camera anymore. Although I may need to dip in to that footage at some point of cause.

Propellor unlike Claudiu and yourellf I didn't have the same kind of playback issues with EXDCAM, although the quality of the footage when played back in FCPX does look effected in some way, kind of an interlaced or SD look?

FCPX is 64 bit and thus very RAM and GPU demanding. I'd never try to run it with less than 8GB RAM. And best graphics card I could afford.