Hi Zaxifone, they are both 256 chips. I checked the m/board site to make sure i could use 512, and it says it can. Bear in mind that without the old 64meg chip that was in there, it was only reading about 290mb????
i will try cleaning them etc, but even when i put them in one at a time they are reading about half....hmmmm, do you think they could be branded incorrectly, that is something i hadn't thought of......
Alamost ceratinly it is because older motherboards only recognise ceratin data organisations in the chips - particularly the difference may be that they only recognise 32 bit data chips. For instance a 512 Mbit chip may be 8x64 bits - or 16x32 bits. On older m/boards the first would work, the second would show as half the true. capacity.
So your 512Mbyte chip would show as 256Mb - plus your original 64Mb = 320Mb.