I have just installed some extra ram into my pc but it wont recognise all of it. I bought the pc with 64mb installed. Decided I needed some more and so bought 128mb stick. in the spare slot i have inserted this 128mb stick, but my pc tells me i only have 128mb total. but surely i have 192mb total? i have tried swapping the slots i use for the 64 and 128mb but still only 128 total. it doesnt matter which slot i put the 128mb in, the pc recognises it, but weather i have the 64mb in the other slot or not, it makes no difference. is there anything i can do to make my pc recognise the extra ram? i am running windows 98 2nd edition and have definately got the right type of memory. could it be my motherboard? any suggestions would be very welcome.
The problem you have is not about units of the same capacity, but a limitation in motherboard design.
Older motherboards (from 3-4 years age) have a constraint on the way they address RAM modules - it's all to do with the organisation on the RAM module, and the type of chips used. Modern modules require extra addressing lines which older motherboards don't have.
The upshot is that you only see half the amount of RAM on the new board. You need a specific RAM module type, sometimes called "double - sided".
Whilst the term "double-sided" is often used in relation to modules with the lower address line requirement, it's not strictly accurate - as even the newer modules can still have chips on both sides of the module.
Not correct, sorry but you can add memory of different sizes, As that's what I have in an old AT AMD K6 500 system three different sizes of SDRAM starting with the big one in number 0 slot down to the small one in number two slot and it is all recognized. There are various reasons why it cannot be recognized you have said that it is the correct memory but is it compatible with the memory that you have already got in that's just as important
My old pc is a Pentium lll 500 with 192 Mb of sdram. One stick is 64 the other 128. I can't remember which was fitted when I bought the pc but had no trouble upgrading it. On the other hand an earlier pc with a Pentium 100 needed its ram to be in matching pairs. I can't remember the type of ram used though.