I Use ASUS Mother board which i use 128 and now want to add 256 indepently both are working but when i add its showing only 256 where i need to changes and wahts problem ? both are 133Mhz.
I assume that if you put either module in the board it will work OK on its own. Have you tried swapping the modules over in the slots, sometimes it helps if the larger module is in the first slot.