Answer: Gold, Silver, Copper
Step-by-step explanation:
Gold is very useful in computers as it can be used for connectors, connecting wires and even memory chips. It is a nonreactive metal and so is not toxic unless it is consumed (and in large quantities).
Silver is another nontoxic metal used in computers to make circuit boards, cellphones and even keyboard components. Finally there is the very important copper which is a useful electronic component for more than just computers. This non-toxic metal has contributed significantly to the development of many things electrical including, as already mentioned, computers.