Hi, I got a second hand laptop (dell inspiron) it has a pentium 4 2.8 ghz processer and 512mb (2x 256) ram. Decided to upgrade to 1gb and bought two identicle 512's but after fitting computer would not boot (blank screen) after experimenting it needs at least one original 256mb card to boot so now I have one 256 and one 512 which works ok but is there any way of using the other 512 that I have paid for?