Computer motherboards contain gold and can be recycled for cash. Recyclers and refiners will purchase motherboards from you for gold recovery and most are willing to pay cash. Motherboards can be taken to these companies whole and generally bought by the pound, working or not. All they want is the gold and other scrap contained in the boards.
Remove the motherboards from your computers. Open the computer case and pull out the boards. You may need to undo some screws or pull out other parts in order to get them out. If you break the board it should not matter as most recyclers will still accept them and pay you as long as it contains gold.
Take your motherboards to a gold refiner or electronic recycler such as Specialty Metals Refiners or B.W. Recycling (see "Resources"). They will pay you cash for your motherboards. You may have to remove metal and plastic before they will accept them; check with the company before taking them in. Many gold refineries will buy your motherboards, but not all are interested in electronic scrap—verify they buy them before taking them into the company.
Sell them at online auctions such as eBay. There is a market for motherboards online. You can sell them by the pound or ship in a flat rate box from the post office. Make sure to know how much it will cost to ship so you can add shipping into your price. The post office can help you with shipping.