No, what I meant was lo and hi density do not play well together...nor does a board requiring lo density (usually the older ) will not work at all with hi density. Both lo and high density come dual sided, and single sided. Single or double sided has little relevance to density, ALTHOUGH double sided is somewhat more likely to be lo density.
No mention in my post re: single or dual sided NOT working together, provided the densities are correct. I have pair of single sided 256 mb HyperX with dual sided 512 in dualchannel right now. All 3 are lo density. Lo density chips are often considerably more expensive than hi density stuff.
And if one stick is spec'd at cas 3, the other at faster cas2, both will default to cas3. You can try manuially overiding that in bios with appropriate choices(usually avoid spd or auto, choosing "user defined instead), and it works sometimes, esp w high erformance quality ram, although the difference will not be perceivable except by benchmark, and even then only marginal. But you know us clockers, we'll go for every fraction improvemet!
