PSU's contain potentially lethal voltages, even when switched off. Exercise extreme care when working inside them! Neither the author or BiT-Tech will accept any responsibility for any damage or harm that befalls from attempting anything referred to in this article. I am not going to cover every little step involved and tool usage, because if you don't understand any of the procedures, then DON'T DO IT! If you kill yourself then don't tell us. You have been warned!

I am going to add a mains switch and a fan speed controller and maybe a little cosmetic surgery for good measure! Because these mods involve drilling and filing, before starting, I recommend removing all the electronics from the case to prevent any loose metal filings from lodging on the circuit board and causing a short circuit. Give the case a good clean with a brush and vacuum cleaner before refitting the board.

The switch and fan speed control are to be mounted under the mains lead socket. The required holes were marked out and then drilled and filed to shape.

Space for the extras Making the holes

The new mains switch will be connected in series with the LIVE wire, (brown wire), running from the mains supply board to the main circuit board. After determining the best place to cut the wire, (fitting the switch to the case and then measuring the wire is the best way to figure out where to cut), the wire was cut and the insulation trimmed back.

The live wire to be cut Cut and strip the live cable

Heatshrink sleeving was slipped over the cut wires before soldering them to the switch. After soldering, the heatshrink was pushed over the connections and "shrunk" using a hot air paint stripper. Be VERY careful not to overheat or melt anything, these things kick out tremendous heat over a fairly wide area.

Wire the mains switch Insulate with heatshrink

I considered the clear red fans "too nice" to be hidden away inside the PSU and decided to replace them with a pair of Thermaltakes. (something of an "anti-mod")? This would allow me to utilise the clear fans elsewhere and the thermaltakes being considerably more powerful, (and noisier), would improve the cooling. To allow control over the fan speed and hence reduce the noise I decided to use a spare PWM controller. The PWM controller was chosen to keep heat generation inside the PSU to a minimum. How the PWM controller is connected into the circuit can be found here. If you just want a Hi/Lo switch setting you could use this simple circuit instead.

Lubberly jubberlyThe PWM controller

The PWM controller fitted nicely and was powered from one of the now unused fan headers on the PSU board. To connect to the new fans 3 pin connectors, a couple of old 3 pin to 4 pin adapter cables were cut up and the 3 pin connectors used.