First it doesn't matter if it is dual or triple channel memory it will still work. But if you would like optimal performance then surely pick of a triple-channel kit.
First question is did you place it in the right slots? All the blue ones..........
You can try just one stick but place it in the first blue slot.
You read the slots from the cpu to the ram, left to right it would be a1, a2 - b1 , b2 - c1, c2 And you want to use a2, b2, c2 for the ram.
Seen this issue many times, not saying it is yours but would be a good place to start. Doesn't the p6t have a cmos clear button on the board and or on the back i/o plate. As i would try everything on auto to start with. Make sure you have a speaker plugged into the board so you can hear the beeps for error codes.
Edited by KILLER_K - 8/2/09 at 3:39pm