The average computer contains around 0.0005 US pounds of gold, which is around 0.008 US ounces, which is also about equal to 0.237 ml of gold.
It takes quite a bit of computers to get a lot of gold from and to get any good amount of money.
You won't make much money off of just a few computers however if you have a lot of computers you can make quite a bit of money from the circuit boards, motherboards etc.
The motherboards of computers is where most of the gold content is contained in a computer so you can easily sell motherboards to scrap yards or E Waste recycling places.
If you have a couple computers it may just be best to sell them as is to a recycling place or remove the motherboards and sell those motherboards for some money.
You average about $8.00 to $9.00 per computer from the gold content.