As far as I know, the C134 works with the M10k only (and perhaps some of the older boards too). With the M10k and laptop drive, there isn't really any extra room. If the M12k has even a slightly different footprint (CF flash, PCMCIA, or other stuff), I'd bet it won't fit. If you're seeing obstructions, that pretty much answers your question already. Sorry to confirm the bad news.