How Can I fix My 256 IBM Ram?

Hi i want to konw how to fix my 256 IBM ram.
it allways let the computer get freez or reboot (restart)
1- If it get freez i can't do nothing no mouse work no keybord nothing it get freez during anything i worked in the computer.
2- some time it reboot (restart) again and again.
I don't know how to fix it.
And if you are Wondering how i knew it is the rame I asked my uncle who is an I.T and i ask a few friend of my father who are also an I.T