Memory problem

I bought some more memory for my (old) system, but it's not showing up right...

I have an ASUS P2B-F motherboard, it says it supports up to four 256 MB DIMMs (PC100), so I bought one that says 256MB PC-100...problem is, the computer only recognizes it as 128MB.  Only thing I can figure is that in the manual it says: "Single-sided DIMMs come [up to] 128MB; double-sided come [up to] 256MB."  The one that I bought is single-sided but says 256MB.  Is my motherboard just too old to recognize single-sided 256MB?

How much did you buy that single-sided 256MB DIMM?

How much did you buy that single-sided 256MB DIMM?

$60, probably too much to pay now that I'm looking on ebay...

OK I guess it doesn't handle the new higher density memory...how can I tell which memory it can take?

This ones' simple.  For equal MBs, the more chips on the module the OLDER IT IS!  You need an older double-sided DIMM.  Good news is they're easy to find.  Better news is your local PC recycler will most likely trade you.

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MEGA-MAN