8GB 1066 RAM Errors Out

I have a Gigabyte MA790X-UD4P motherboard and I just bought 8GB of G.Skill RAM. Everything in BIOS regarding the RAM was on auto which put the RAM @ DDR2800 so I changed the memory voltage to 2.3 and set the clock speed to x5.33 which put it at 1066 and corrected the timings to 5-5-5-15.

I then put it into Memtest86 and less than a minute in, errors are coming up constantly. So then I tested the RAM sticks in pairs and both pairs came out ok individually. Also, I don't get any errors when in DDR2800. Is there something I'm doing wrong or should I return it and get a different brand. I was looking @ getting these: OCZ Blade