I can't speak for Uruguay, but I've shipped quite a few boxes including a GPU, Bose Soundlink Mini and a PSU (All new except for PSU which was also in the original box) from the US to Sri Lanka with absolutely no problems. Postal services tend to be shaky with this kind of thing; there are hundreds of stories about things simply lost in mail, as sending packages through mail is simply not done in most developing countries.
Instead, use a air-transport agency like DHL (If you need to get it quick) or a standard shipping agency that'll pick up the goods in the US and ship to Uruguay, where you have to go to their warehouse to pick up the stuff. Using this method you do have to wait while customs in your country open your boxes or X-ray them, but I've never had a problem. Usually the worst is they take a few cheese boxes and a bottle of shampoo or such out of a fully packed 4'x2'x2' box. For the time where I shipped the electronics, they only asked what it was and were fine with it when I said a relation sent a graphics card for me to play computer games; no taxes were charged. The important thing is to designate the stuff is for personal or household usage, and to answer only what they ask in as broad a fashion as possible, and try not to go into detail.