RAM problems

[zu6fx]

Hi.

I've recently bought a new DIMM for my pc but I've been having some problems, I have an MSI H55M-P31 motherboard, its DDR3 and has 4 slots and supports up to 16gb, I have 2x1gb and 1x2gb, it work fine but as soon as I add my new 4gb module my pc doesn't start up, though if I take out all of the DIMM's except for the 4gb, It works fine.

Is this a usual problem? If so is there a way to fix it? Any help would be much appreciated.

Thanks.

 

[johnb35]

Are the sticks the same brand and timings? If not, then the motherboard is having issues with them being different.

 

[zu6fx]

Yes the sticks are the same, same brand and both are DDR3-1333, I did read up on both the sticks and all I could find that differs is the size...