Need help with corsair ram and striker 2 formula mobo

I am having trouble in booting using both memory sticks. I will call ram mem a and mem b because with one it boots ok to bios but other one not.Here is what i get:
If mem a is inserted alone it boots to bios ok.
If i instert mem a and mem b it wont boot and say det dram followed with short beeps
If i insert only mem b it wont boot and makes long beep.

I tried setting mem speed to 5-5-5-15 and volt to 2.1 with no luck, maybe i was doing something wrong :S

Here is major parts from my pc:
asus striker 2 formula mobo
corsair cm2x2048-8500c5d ram
intel core duo e8300 cpu
corsair hx620 psu

Any suggestions appreciated.

Jup, tried it in the same slot.