Well, you can try that GPU, but it's a gamble if that PSU is quality enough to run the card under loaded conditions. As I said, most OEM PC makers like Dell use really crappy power supplies that do not come near the maximum loaded wattage rating that they have listed on the side of it. They are only designed to the factory PC spec needs and any upgrades requiring more juice may cause problems. I would invest in a 400-450W PSU just to be on the safe side. Something like this:
https://www.newegg.com/Product/Product.aspx?Item=N82E16817438082