Supposedly you can put in two 2GB sticks and it'll "work", but the machine will physically recognize only the first 3GB and will not 'see' the last 1GB. This is not a result of the "32-bit 3GB limit" (which isn't really a 3GB limit anyway), but is a limitation of the E1505's chipset. Even with a 64-bit O/S you still won't be able to use more than 3GB.