I have the same mobo. Since I use the Tascam FW-1884 it *must* use a TI chipset. I'm on F5 and get about the same results as you with a PCI-3 ADS Pyro card (TI Chipset).
I suspect that this mobo needs a better BIOS. I tried F6 and F7a. Both were worse. My mobo came with F3 which up in 1100 range. At least now, on Rev F5 I get ~500 like you.
Not happy as my previous Q6600 mobo was around 50 with the onboard TI chipset. I just "assumed" Gigabyte was a die hard TI Chipset user.
My bad. Sadly, I may never buy another Gigabyte mobo again.