256 MB Ram shown as 128 MB

[luismiguel]

I’ve bought 2 DIMM PC133 of 256mb each to improve computer’s performance but the system only reads 128mb from each. Do I have a problem of incompatibility with bios (it’s an old version of award/phoenix)? What can I do to optimise the system?
The dimms (2) that I had installed were of 64mb each with PC100 frequency reference.
Should I update my computer BIOS?

Hope to get some support from the community...

[Rainbow]

If you have board with older chipset (like i440BX, i440LX), single sided (8-chip) 256MB modules do not work properly - you need double-sided modules (16-chip).