I don't know exactly which motherboard you have, but I would venture to say the KT7, or KT7 Raid?? If so, did you install the VIA drivers for the motherboard, as these drivers include the IDE, AGP, and ACPI drivers greatly needed for everything to work OK. If you haven't, install them, you will notice a difference. As for the power supplies, they may or may not be sufficient. The older power supply may have been 150W, but they just may not be able to sustain the amperage and complete power draw. I would feel comfortable more with a single 300W unit that you know will work! Also, what drive are you using? If it is an ATA 66 drive then all is OK, but if the drive is ATA-100 then you may want to get the utility disk for the drive from the manufacturers website and set it to ATA-66 mode and see if it improves anything.