I have the exact same thing happening to me yesterday with my x64.
The previous day I used the system normally and then switch it off. Yesterday I tried to switch on and the drive is non recognised by the bios.
tested with different sata ports, sata cables, power cables... but no luck.
I have been using it for 11 months with no problems whatsoever and with the same settings. My X64 is still of an old batch wit the first firmware an i never even tried to do a firmware update (no much point to enable trim as I'm using winxp). I'm not using ahci as it is not supported very well by my motherboard and slows down the boot process. But yesteray I also tried to switch to ahci.... without solving anything.
The "funny" thing is that when the drive is plugged in, the bios tries to detect it and stays there fo 15-20 seconds before saying that there is no drive attached. If it is unplugged the bios takes a fraction of a second to detect that nothing is plugged in the sata port.
When the x64 drive is pluged in there is also a glitch in the recognition of one of the other drives in the system, which is only detected if i go in the bios and manually try to detect it.
For the avoidance of any doubt... I did try to manually detect the drive in all the 6 sata ports of the Mobo and to detach the other drives.
Currently I have to use my old raptor.... and it feels Slooooooooooooowwwwwww
Shall I request an RMA?
If so...Shall I indicate the link to this post?
In case of rma... is thre an "expiry" date for the rma number?
The reason for my asking is that I live outside USA and will be able to send the drive back only in 3 weeks time when I visit the States.