"Alan Garrison" <aeg@lbwl.com> writes: > What may not be backwards compatable are the older DIMMs that > are rated for 10 or 8ns but are not PCxx. Unless I misunderstand your point, I think you mean that older DIMMs are not forward-compatible: they won't work in PCxxx motherboards. PCxxx DIMMs, or at least the ones I've used, are indeed backward-compatible; I've successfully used PC100 DIMMs in my pre-PC100 PII motherboard.