Memory compatibility problems

[Tocapet]

I ordered a pair of 1 GB PC3200 DDR400 sticks and they sent me a pair that say
MDD400 128X64. These are not compatible with either of my 2 machines running Win7 64.

What's the difference?

 

[bobkn]

I've not seen it before, but MDDR is mobile DDR.128X16 implies that it's a high density format as well.

I doubt that it's compatible with most desktop PCs.