Asus P5GD1 Pro + P4 3.0E @more than 215 FSB Problem SATA II

Serial ATA drives can be a problem for overclocking. The following is a quote from an article on the Intel 915 chipset, which you have, describing your problem;

"For overclockers, there is, however, a flip side to using SATA drives. Many motherboards that are favorites with overclockers do not overclock as high with SATA drives as they do with IDE. This primarily applies to Intel chipsets that integrate SATA in the chipset and virtually require a fixed 33.3 PCI bus for SATA drives. At high overclocks, the SATA lock often seems to get compromised and slight drift means no SATA hard drive."