I bought a PE2950 with 4GB of RAM, and now we are trying to upgrade it to 6GB. The memory DIMMS are all of the same speed and size (1GB, 533mhz), but there is no way that the BIOS recognizes the whole 6GB, it only sees 4GB and tells me that there are not properly paired memory banks, or that they are not the same technology or speed.

How can I achieve 6GB with 1GB memory DIMMS? Or is it simply not possible?