Today we are taking a look at the SilverStone FX500, one of the very few Flex-ATX PSUs in the market. It boasts a magnificent 500 Watt maximum output at a quarter of the volume a typical ATX unit requires and is 80Plus Gold certified, making it practically the best-engineered Flex-ATX unit available today. But channeling 500 Watts through such a small PSU also brings some noticable cooling challenges.