Can't get dual channel RAM to work?

[walkerb0h]

My system won't post when I have both of my kingston HKX1600C8D3K2/4GX in the A2/B2 or A1/B1 slots. It will boot if I just have 1 of the 2gb sticks in B1 or A1. My motherboard is 880G Extreme3 from ASROCK. My processor is an AMD Phenom II x4

When I put both sticks in the mobo led returns a D0(Go to flat mode with 4GB limit and GA20 enabled. Verify the bootblock checksum.)

I've tried swapping the ram positions and changing some BIOS settings.
Memory Controller Mode:unganged
Bank Interleaving:Auto
Channel Interleaving:Hash2
CAS Latency:9
TRCD:9
TRP:9
TRAS:27
DRAM Voltage:~1.75
Memory Clock:800Mhz DDR3_1600

I'm afraid if I keep playing with BIOS settings and plugging/unplugging my RAM I'm going to break something, where am I going wrong here?

Thanks