when i start my pc it beeps 3 times, never knew why til now, how exactly do you reset memory, i'm new to all this, thanks very much Mark

you don't reset memory. you open the case, take out the memory, then reseat it in its slots firmly

unless that's a reference to the BIOS in which case you would remove the CMOS battery and short the leeds together then replace the battery. Although you might want to view what the current bios settings are now.

What memory cards do you have? If you have two probably one is placed the wrong way. Try both what kkk and rayman said. Or it could be your memcard that is broken. Calculate how much memory you should have by adding each memcard space and compare it to what to the "Total Physical Memory" property in the System Information program in the System Tools in the Start Menu. If one of your memery card have a problem the two numbers should be unequal.

many thanks for the help i'm lookin at it now

Beeps usually come from BIOS but what they mean depends on the BIOS manufacturer (listed during boot-up). If, as I assume, you have decided this might be a memory problem and reseating it doesn't work then try this: Take out each stick and run a clean soft pencil eraser over the edge contacts (so that there is no oxide - they should shine). It's too easy to leave bits of pencil eraser behind, so get a small artists paint brush and run this over the edge connectors afterwards. Derek