Seasonic S12-II 500W PSU

Results

Seasonic rates its PSU to 50˚C (Addendum 25th June 2008: Seasonic contacted us and told us the PSU is rated for 100,000 hrs at 25ºC), and as expected the S12-II performs exceptionally well; we found it to be consistently very quiet and very cool to touch, with only an extended session of 100 percent load warming it up a bit.

In a very quiet case, you will be more aware of the fan spinning rather than just air movement because it is slightly noisier thanks to that ball bearing, however it's certainly not intrusive and you'd be hard pressed to hear it above a few hard drives, CPU fan and graphics card.

The fan is thermally controlled to react to the increase in load (and therefore temperature), so it does get louder as the load increases, and while it wasn't silent (as in, inaudible) it was still very tolerable.

As you can see below in the results, the quality of output is exceptional as it reads all green voltages even up to 100 percent load with 12V and 3.3V/5V weighting tests. The power factor correction (PFC) is consistently above 98 percent, and the efficiency is always above 85 percent, apart from heavy 3.3V and 5V load which is an unlikely event in current PC environments.

Compared to the Corsair VX550 results, the PFC is slightly higher overall, but most of the likely loading scenario's are about the same 85 percent efficiency performance. Only the 3.3V/5V weighted at 100 percent load is considerably better than the Corsair, and by quite a margin: 83.7 percent versus 79.7 percent efficiency.

Overall, we can't fault the Seasonic S12-II 500W – it not only does what it says on the tin, but it's also very competent in how it achieves it.