About the slots, it doesn't matter which slots they are - they are just a different colour fulfilling the same purpose. Dual Chanell RAM has to be in the same colour of the slots AFAIK, leading me to the thought the mobo is faulty.
I will try that BIOS thing you mentioned.
Edit: Not sure what you meant, but you wanted me to check out 2 sticks after I perked into the BIOS to see if one stick is running at it's rated speed, right ?
In that case, I can't do that, because at the moment there is no remote way for me to use 2 ram sticks, as one black one is blocked, 2 blue ones dont work, so im left with only 1 black one.