memory problem

[jenkin1988]

Hello.
i have motherbord GA-P55-UD6.
i buy 4x4GB memory stick and  put it to slot 1/2/4/5 after it pc not up and i get "2d" erorr code.
after it i put 2 x4GB in 1/4 slot, and all work fine.
i upgrade bios to F11 version.
i try all option on bios in memory and not work.
voltag for memory 1.5v.

Thanks for help

[dmdilks]

Try them in 1, 3, 4, & 6. Or try and move them around till boots.