can you mix different pc # rams, like say a 2700 512mb in one slot and a 3200 512 in another?

Yes as long as you put DDR with DDR, SDRAM with SDRAM, but it will run at the lowest stick speed, being 2700 512mb, on some mobos mixing memory works ok, on others it wont work, at all, or randon problems.

The one thing you generally should avoid, however, is mixing RAM speeds in the same computer. In theory, if you mix RAM speeds, all of the modules should clock to the lowest speed; but in practice, mixing speeds (and sometimes even brands) in the same PC can occasionally cause system instability.

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