While the computer industry has made great strides in the past few years, most generic power supply manufacturers have not kept up. What I mean by that is modern processors (AthlonXP, Pentium 4's) draw their power from the 12V line, however most PSU's on the market are still built around the 5V rail where the Pentium 2-3 processors drew their power from.

According to Intel, a Pentium 4 3 GHz processor draws approximately 9.7 amps off the 12V rail itself, if you're using a generic 300-400W PSU that potentially leaves very little room for any other devices. You can guess what happens when the processor does not get enough current; hard locks and spontaneous reboots when under heavy load.

Inside the SS-400AGX

Seasonic uses a detachable 80mm SuperRed CHA8012CB-A (closest I could find) 80x80x20mm fan to ventilate the internal components. At full load the fan spins 3000 RPM and pushes 32.5 CFM while producing 34 dB of noise.

To help keep vibrations at a minimum, Seasonic have placed rubber spacers between the fan and casing of the power supply. During testing, the power supply was absolutely silent and the only way we could hear it when I placed my head within 10 cm of the fan!

Even though Seasonic claims that the SS-400AGX is one of the cooler running power supplies on the market, with few ventilation holes I have a hard time seeing how the PSU can meet that claim. Even with the ambient temperature below 20 degrees celsius, the air coming out from the power supply was quite warm.

Unlike the PC Power & Cooling Turbo-Cool 510-PFC we reviewed earlier, the innards of the SS-400AGX are relatively sparse. The enthusiast might be a bit disappointed to see that Seasonic does not have any internal adjustable potentiometers - but realistically speaking, letting users poke around with the voltage levels can be pretty hazardous unless they are educated on the matter.