I get this with my external dock from time to time, one reason is the eSata lead has come loose at the MB end of things, I have a pci bracket that then goes to the board via a lead from it.
The other iirc is that it doesn't work unless the bios is in AHCI mode, if yours isn't and Windows was installed without the driver you will need to do a simple hack to enable it, let me know what you find first though, I don't want you messing with the O/S if it doesn't need it.
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DOING ANYTHING I HAVE SUGGESTED IS AT YOUR OWN RISK, NEITHER I NOR SEAGATE TAKE ANY RESPONSIBILITY, IT'S YOUR CHOICE TO DO WHAT YOU FEEL IS BEST FOR YOU
