Hi guys new here. My computer is from 2001 with a processor upgrade during that time span. Now my computer after its been on for a few hours starts rattling and instantly just shuts off. after it shuts off, it makes a metallic smell which is very strong. After a while of being off it would turn on, but it would not turn on right after it turned off. But when it turns back on and is on for a long time again it shuts off in t he same way.