Muze byt.
Mam tu jednu starou MSI 6153 a to same - pozna pouze 2x256. Vic ani tuk.

edit: ted se divam na tu tvoji:
maximum memory:
512MB using 400MHz DDR modules
2GB using 333MHz DDR modules
3GB using 266MHz DDR modules

This system only supports 4 banks of 333MHz DDR memory.
If two double sided DIMMs are used, the 3rd socket is disabled.