Hi Dalo Harkin, Thanks but I'm afraid all that you have told me has fallen on barren ground. I haven't a clue what you just said. I can just about manage to get into BIOS without making a mess of things. When I did look in the BIOS, Phoenix by the way, there was no mension or means of altering timings or voltages. All I wanted in the first place was to buy new RAM that I could plug and play. I have had a reply from Kingston, something about overclocking. ( Straight over my head ) I am now hoping to return these modules and hopefully get the correct replacements, 4 X 1GB by the look of things from Crucial. A bit more expensive but hopefully will work.