I using a WD 80GB ATA100 Drive w/ 8MB Cache DMA is ON . HDD-Tach is showing a Transfer Rate Graph between 60MB/sec and 30MB/sec . The graph is clean ,no spikes , so the drive runs normaly . The Average Read Rate is 50MB/sec with 9% CPU utilisation. So it's not the HDD . Also ... I thought that "CPU Microcode" section in BIOS is only related to the functional specification of a new revision of the CPU like : the new name of the CPU , the multiplier and FSB setting and the voltage .