Okay, I just built my first computer, and when I booted it up for the first time, it couldnt recognize any of my 2 SATA HD drives.
I'm using an asus k8v se deluxe motherboard with 2 SATA drives.... I have one of the drives plugged into the PRI_SATA port in my motherboard, and the other into the SEC_SATA port. Then I have them both plugged into to a serial power converter (it came with the motherboard, it plugs into two serial power things and converts it to 4-pin white molex). Then I plugged the white molex into the video card power cord that is split (its a radeon 9800 pro)... By split I mean that its a has a 3-way connection... one part of it connects to the PS, one to the video card, the other to the harddrives. (thats how it said to connect the video card power supply).
And when it's booting up it doesn't detect any HDs after I press DEL for BIOS setup... and even after pressing TAB at a certain time to get into the place to make arrays, it says that they arent connected or dont exist. (similar picture below -except it says there are no drives)