Can we get a complete list of the components used in your system. Please confirm you are using the AMD SATA ports. The SB850 drivers are installed or updated with each new Catalyst driver. If you are using an AMD/ATI video card you are already installing these drivers. Things get a little confusing if you are using a Nvidia video card because it looks like the SB850 drivers are not down loadable separately. I would guess the Catalyst driver would allow the installation of the SB850 drivers even if you are using a Nvidia card but I have never tested this. Hopefully a AMD guy will either confirm or deny this. By reading over your posts it sounds like you do not have a driver installed fo the AMD SATA RAID controller. In the link you posted for your motherboard did you install this driver? "AMD Chipset Driver (include chipset \ sata raid driver)"? You will never see the full potential of the SB850 with out the drivers installed. What strip size are you using as it can make or break RAID 0 performance?
Gigabyte may need to release a updated bios to improve SB850 performance. They may have already does this and you may already have it but I can't say for sure as no bios claims improved performance. There is a beta bios "FEB" that has updates for a new RAID ROM. It also looks like the FD bios adds support for a new revision of the SB850 southbridge. What bios did your board ship with? If it was older then FD you may have a older revision of the south bridge which could possibly hurt drive performance.
Bill
