Have a Gigabyte P35 DS3L board on which I'm running XP SP3. I've noticed inconsistent data rates on a SATA drive as measured with HD Tune. It'll start out fine, say around 75 mb/sec, then will drop to 2 - 5 mb/sec. Same drive in my Win7 machine doesn't do this. Can an aging SATA header/circuitry cause this?