I have a Sony VAIO laptop I'm working on a long with a similar model I ordered for parts. When examining the installed memory in the two units, I found it odd that the primary memory module seemed normal, with 8 memory chips (4 on each side), but the secondary module had only two on each side.

I first I thought that this was an upgrade made by the owner at a later date, but both laptops had the same kind of modules. Out of curiosity, I tried various pairings. Here are the results. 8 indicates the 8 chip module and 4 indictes the 4 chip module. The arrangement is SLOT1 + SLOT2 = capacity.

8 + 4 = 128 MB (standard configuration)
8 + 8 = 128 MB
4 + 8 = 64 MB
4 + 4 = No POST screen

It seems as though these high density modules will only work in the second slot when there is a normal module in the primary slot. They cannot be used individually, in pairs, or in the primary slot.

Does anyone know anything more about these special modules? My guess is that it was cheaper to manufacturer these high density memory modules, and that they are simply unrecognizable by the BIOS until it it bootstrapped by normal low density memory.