So, by now everyone knows (whether they wanted to or not) that I've been trying to figure out what's going on with my computer's RAID array, and it finally occurred to me to (gasp!) use a different benchmark! So I fired up HDTach on my machine and on my father's machine, both of which have the same NetCell RAID controller (but different hard drives), and here's what I saw. His machine: My machine: And here's a scan of a machine with a single IDE disk, just for comparison: Doesn't really look like I'm taking a performance hit at all, does it? Granted, I'm not getting substantially faster transfer speeds than he is, despite having bought extra-expensive Raptors for myself and not for him, but then his disks are newer and have a higher bit density so that's not too surprising. I do have a slight edge on seek time, though, and the average read throughput bears out that I wasn't a fool for buying a cheap (but all-hardware) RAID controller -- the speed is almost exactly double of the single IDE disk, which is exactly where it should be for a three-disk stripe+parity array. So this is the last nail in the coffin on the theory that there might have been any kind of hardware problem on my machine -- though the nosedive on his machine near the end has me worried, but I think that was just a fluke. Since HDTach uses its own drivers to access the hardware as directly as possible, I guess that means what I have is either a driver problem -- or a PCMark problem, because PCMark is the only thing that sees a performance drop. Is there a way to totally remove the registry keys that store hardware and driver info, to force Windows to re-detect it all from square one? Running Windows Repair didn't seem to do that, so as long as I've got a working backup of the registry, I might just be in the mood for a little mass-deletion if only I knew what to target. - - - On a side note, the workstation I have at work performed atrociously -- something like 25MB/s. Yeah, that's totally worth $2000 in SCSI RAID hardware. Glad I wasn't the one who specced it out.