Serial ATA HD wont show up

Hello all.

Last night i put together a computer which included a 160GB Maxtor Serial ATA hard drive.

This morning, everything was working (including HD) so i installed XP Pro SP2.

MY Power Supply is a Thermaltake 480W with adjustable fanspeed control or something like that.

After i istalled some drivers and rebooted a few times i lowered the fan speed on my PS.

Now after i did that my HD will not show up in the bios anymore.

I tried switching and reconnecting cables and still nothing.

Even loaded XP again from the CD and it tells me there is no HD.

So even though it's in there, i have no HD.

If this has happened to anyone before and you've fixed it, please let me know.

Thanx in advance.

-Pablo