If you can’t do the whole metal pole in the garden thing, you can try the following…
One of the problems is that your computer probably has rubber feet, that insulate it from your floor. You are touching the floor, so as long as the computer case does too, you should theoretically have the same earth.
Easy solution (worth trying at least) is to stick some tin foil (aluminum foil) under one of the feet (computer feet, that is, not yours) and make sure this then connects to a metal part of the computer case (which is connected to the earth part of the internal power).
Sorry, I should add that if your computer is on a desk or something, rather than directly on the floor, then try putting the tin foil under the table leg and then trailing a wire up to the computer case.