Gents, Any opinions on if it's the SATA controller or Maxtor that's going to go back to DABS?..... Please help, as I'm not sure which one is the cause. Thanks for any thoughts or experience.... I bought a single Maxtor DiamondMax Plus10 300GB SATA hard disk and DABSVAL SATA RAID0+1 PCI controller (http://www.ivmm.com/eio/products_sata_pci_host.html uses a Silicon Image 3112A chip; very common on motherboards, intel boards, etc.). Win XP Pro recognised the SATA PCI card automatically and the on-cd drivers aren't used if I try to upgrade the driver, so I guess I've a not too out-of-date microsoft approved driver set. I'm currently copying about 37GB on to it from my existing WesternDigital PATA 100GB hard disk, at about 30MB/sec, as expected from that 100GB drive. I have a strange issue, in that each minute or so, cpu drops from 90-99% down to 1% for about 5 seconds and the copy remaining time estimate jumps (throughput dropped), then the whole desktop including usb mouse appear to hang for exactly 33 seconds, until it carries on. i.e. 22:47.32s cpu drops to 1%, 22:47.36s desktop hangs, 22:47.45s resumes 99% and fast copying. 22:51.08s cpu drops, 22:51.12s desktop hangs, 22:51.45s resumes 99%. 22:52.34s cpu drops, 22:52.38s desktop hangs, 22:53.11s resumes 99%. 22:54.22s cpu drops, 22:54.26s desktop hangs, 22:54.59s resumes 99%. ... The gaps vary, but the 4secs io pause then 33secs hang are consistent. It did originally fail at 99% of original formatting (full format, to check it better), but I had undervolted the machine's cpu from 1.7v down to 1.5v (at which it has just run 24/7 for 4 weeks flawlessly before adding the SATA card and Maxtor drive). I'm testing back at 1.7v. The machine is a Pentium3 750MHz, on an ASUS/intel botherboard, 512MB running Windows XP Pro SP2, all updates and AVG anti-virus. D-Link gigabit, usb2 card, usb2 nebula usb (not running), media server for netgear (showing no cpu used). thanks.