I recall reading years back that the 5500 (which uses the same logic board but in an AIO) could unofficially support 128MB DIMMs to give a maximum of 256Mb... that being said, i cannot verify the legitimacy of these claims. Unfortunately I am not even in a position to test the theory, as even though i now have 128Mb DIMMs that i didnt back then, I no longer have a fully functioning 5500 as a testbed.