ddr3 detection issue

[QuestioningGuy]

I bought some still in packaging ram (kingston hyperx predator ddr3 1866mhz 2x4gb (hx318c9pb3k2/8)). It doesn't seem to detect two particular sticks out of 6 that i bought. But it does detect all 24gb of it in cpu-z and aida 64, not in windows or the bios. Is the ram faulty, or am I missing something here?

 

P.S I did test all of the sticks one by one, and two of them seem to be malfunctioning. I did test triple channel with some mismatch ram and the 4 functioning ones, and it did work, detected all 24gb in the bios

 

P.S.S

Asus p6t deluxe v2 with a Xeon x5675, not much else matters i suppose