New RAM won't work for my computer?

[mikael.s.n1]

Hey everyone

I recently bought some new ram for my computer, but it won't start up when I put them in.

I am using a P8P67 Pro as a motherboard, and I already have 2x4 Corsair 1333 mhz RAM inserted to the A2/B2 slots.

When I tried to put new ram (I have tried 2 different kinds now) in the black slots (A1/B1), it wont start up. I have checked online and they should be compatible with the motherboard, so I cant figure out what the issue is.

Also when I removed my new ram and tried replacing them with my old ram, they still didn't work. But then when I inserted my old ram into the old place, THEY didn't work somehow?
I tried moving them around a bit and finally got them to work, but I don't really understand what the problem is here... I could really use an 8gb upgrade.

Help is definitely appreciated here

 

[DRagor]

The fact that new RAM is compatible with motherboard is meaningless if you try to mix it with other RAM. You never know if any set of sticks will work with another set of sticks, even if both sticks are same models. You didn't provide enough data on both new and old RAM to compare them, and such a simple difference as different CL might make them unable to work together.
One more thing - when playing with different RAM setups, reset CMOS after each change to force full hardware check - that should let you avoid a problem you observed (old RAM worked in A2/B2 and now don't).