I assume you built the computer and that you did "NOT" repair a computer.
If you built the computer for use as a business asset in a business that you own, then the entire cost of the computer is entered as such in the Business Assets section of the SCH C and it gets depreciated over 5 years.
Take note that you can only claim the total cost that you actually paid. The value of your time and your labor is not included in the cost, since your time and labor is not taxable anyway.
