Dual channel errors

hi guys,
Well after owning the asrock 890fx delux 3 (amd/am3) for almost 5 months i have had no problams until recently.
After trying some diffrent ram for a friend (sector5, ddr1333 patriot mem) on my mother board to see if his ram was bad (which one of the stick was). I renstalled my own ram in dual channel mode and started getting crashes, they started to get worse and worse up to the point where i couldnt even get to the bios. Memtest would show error at random times and would just freeze and I couldnt even get out and had to hard reboot, this was in dual channel mode. but in single channel mode it ran fine with no erros. so i put them in in single channel mode and I have no problmas. I have tried a diffent cpu (same make/model) renstalling the bios/clearing the cmos/ trying my ram on a diffrent computer(mobo) to see if it would run in dual channel mode... which it did with no errors.
I also renstalled the ram as stated with the first stick in dimm1 making sure that it runs ok then installing the second stick in dimm2.
I also made sure all the timmings where correct and voltages were correct.
nothing has changed other than trying that diffrent ram.
So i am stumped..... How could testing diffrent ram, then putting my old ram back in cause my mobo to not run corectly in dual channel mode? I thought the dual channel controller was on the cpu.
could my bios have gone bad?

I have contacted asrock and they are sending me an RMA ticket but i just wanted to see if you guys know of anything else I can try. B4 i ship it off
thanks
mack-attack

asrock890fx delux3
amd955 cpu non overclocked
g.skill 1600(2x2)=4gb (my ram)
750watt pc power and cooling
asus 5870 v2
samsung 500gb hd
win7 64 bit ultimate