Windows 7 - Sabertooth x58 not detecting all 12gb of memory

I have sabertooth x58 and 6 sticks of 2gb corsair XMS3 DDR3 1600 MHz RAM 12GB (6x2GB) 8-8-8-24 model TR3X6G1600C8. I can not get 12gb to show in bios...only 8gb show up and I checked each stick one at a time....confimed that they all work....
Also I noticed that when I was checking each stick one at a time in bank a1, computer would not postwith any stick. All sticks posted fine in b1 and c1. Also when i use all 6 sticks only 8gb show up in bios, but in cpu-z it sees all memory...weird...
I can not even get it to go triple channel, when i tried 3 sticks in triple channel setup only 4gb would show
right now I have only 4 sticks running on bank b1, b2, c1, c2...running dual channel 8gb
this is the only configuration that will post.....no sticks in a1 or a2 shows up....Please help me!!!!!

Overclockers Forums - The Performance Computing Community
i4memory.com - different look at memory
These two sites have a lot of information on your problem. I have tried them all and none helped me but they might you.
Many many many people are having the same problem.

Why aren`t you calling the manufacturer ?

My Intel Dealer installed various sticks of ram and updated the bios he agreed with me it was the mother board.
He removed it and sent it back to Asus. We waited for weeks but when it came back he installed it and I still have the
same problem. I did all the things those sites and other tried, no luck.
I did find another site today. Their instruction were to loosen one corner at a time on the heat sink
to see if that would help. I did, no help.