Lost HardDrives when OC CPU

My computer works great when it is running at default speeds but when I try to overclock it even by one MHZ the bios does not detect either on of my harddrives. They are connected to SATA 1 & 2. One is an SATA harddrive and the other is an IDE HD with an SATA converter. I have tryed other configs but nothing works. Can anyone help?

in soft menu there is an option to select agp ratio, select fixed, might help

Thanks that worked I have never had to do that before but it worked. Thanks