Computer wont boot with ram in dual channel

[asimons11]

Build:
MB: Asus M4A79XTD Evo
CPU: AMD Phenom x4 3.4ghz Denab Black Edition
Ram: GSkill Sniper 1333 4gbx2 8gb
PSU: 500 Watt
HDD: Western Digital 500gb
CD/DVD: Liteon
Operating System: Windows 7 Professional

So here is my problem... This is a new build that will not boot/post when i install the ram in dual channel configuration. The led's come on, fans spins and hard drive works but thats it. My ram slots are set up in this order: Channel 1a- blue, Channel 1b- Blue, Channel 2a- Black and Channel 2b- Black. Dual channel is either 1a/1b or 2a/2b.

Computer works fine when:
1) one stick is installed in any single ram slot.
2) one stick is installed in channel 1 (either 1a or 2a) and one stick in channel 2 (either 2a or 2b) NON DUAL CHANNEL.

I have Rma'ed the ram, has this problem with both sets.
I have run a 15 hour memtest 86 test on both sets, no errors.
The computer seems to work fine when i bread board it, i have gone through the whole computer many times trying to make sure it isnt shorting out.
My ram is compatible with my MB, called gskill and they confirmed it.
All components are brand new.

This has me pulling my hair. I thought i had this problem solved. The computer booted fine about 15-20 times in a row. Today i went to use it and it didnt boot. Pulled one stick and it boots fine. Shut it down, tried dual channel and once again it didnt boot. Now im running both sticks, one in each channel (not dual channel) and its working.

Im leaning towards a bad MB...

ANY HELP WOULD BE MUCH APPRECIATED.

 

[asimons11]

also, im running the latest bios version and i ve loaded default setups just in case it was a setting issue. problem still persists.