I should first of all make clear that the ST45SF-G is an SFX PSU and is, as such, handicapped in performance; that is, compared to ATX PSUs since all of its components need to be extra small to fit inside its Lilliputian case. It is also quite strong for its footprint, and a fan with high RPM had to be used to move the hot air out of the case. That, of course, leads to increased noise levels. Regardless, its high efficiency rating requires, in order for 450 W of power to be generated from such a small PCB, lots of components that need to be installed into a really tight space, and that seriously affects air flow and heat generation, especially because a larger fan wouldn't fit. Instead, Silverstone had to use a high speed 80 mm fan. Silverstone, regardless of the high ripple on the minor rails, surely hid more inside of this PSU than meets the eye. The unit managed to deliver 500 W at over 45 A °C ambient while keeping an overall tight voltage-regulation on all of its rails (the +12V rail really managed to impress here) which is not to be taken lightly because Silverstone's ST45SF-G is an SFX PSU. Efficiency was very good at low loads, although I would like to see higher efficiency at 20% load. Nevertheless, I should note that efficiency will be higher with 115VAC input rather than 230VAC input at low loads. This includes a 20% of max–rated-capacity load and means that the PSU is, indeed, 80 Plus Gold compliant at normal ambient.

To wrap up, the ST45SF-G is, to my knowledge, the only contender in its category since it is the most powerful and only Gold-certified SFX PSU. If you need a powerful and efficient SFX unit for a strong home-theater PC, the ST45SF-G is your only option. It may be a little expensive, but the general rule of "smaller is more expensive" applies to hardware. Don't forget that this units packs a lot of features including a fully modular cabling design, something that is crucial with small cases inside of which space is a commodity.