First thing first. Doing this mod will invalidate your warranty. PSUs can be dangerous and some of the components, especially those on the Primary side, can carry lethal charges. Only undertake this mod if you are really sure you know what you are doing and understand the consequences. I accept no liability or responsibility if you void your warranty or fry yourself when touching or worse still licking a primary capacitor. There can be a few reasons why you'd want to swap the fan on a PSU:- 1) To fit a slower quieter more effective fan to reduce noise. 2) To replace a fan which has become noisy due to failing bearings. 3) Make it look nicer. 4) Just for fun. My reasons are mostly in the first category but also in the fourth, yes I like this sort of thing. Discharge the PSU. There are a couple of ways which are recommended to do this. Some involve leaving it switched off at the mains for 24 hours, another which involves using resistors to dump energy out of rectifiers and caps. I went for the unplug and hammer the case power on button a few times. I don't intend touching anything apart from the PSU case and fan and maybe a fan wire or two. My Power Supply, the FSP Aurum 700W is a 80 Plus Gold unit that achieves 91% or thereabouts efficiency at the loads I put on it. The stock fan is a 2,400 rpm model which is wired to an rather aggressive fan controller. I've checked temperatures and the differences between case and rear PSU external temperatures never go more than 3 degrees at any load I can put on it. I'm thinking FSP have gone very aggressive with the fan assuming that Joe Public will want it to exhaust system heat as well as PSU generated heat. For me in an Antec P183 this is not as issue. I should also add that the noise generated by the Aurum is not particularly high in any regard but is high compared with the rest of my system with no fan ever over 1,000 rpm and suspended hard drives inside an insulated Antec P183. So I needed to decide which fan to replace with. In the end the choice was a now defunct Scythe S-Flex 1600rpm or the one I went for, the Enermax Magma. The Magma has a 85 degree C working temperature, 100,000 hour MTBF and is 1500rpm and pushes decent air and comes in under the current used by the stock fan (0.45A vs 0.4A for the Magma). Perfect. Your Power Supply may be different, have a different fan, run hotter or colder so your mileage may vary. Remove the four PSU case screws to get at the inside. One of the screws may be covered with a Void sticker. Remove the sticker carefully, you may be able to reapply later. The casing may need to be prised from the top if it's anything like mine as the sides are kind of tucked in. The stock fan. The power regulators -- basically this is what needs cooling (hence the big heatsink) Unfortunately the FSP Aurum has it's fan wires soldered directly to the PCB and I can't just shove the 3 pin fan header connector in place of the stock fan. So I need to cut the wires and stuff. Oh joy. First thing first let's identify and understand the wiring. A normal fan connector. And a modded Magma connector. So cut the wire and mark as appropriate. Bare and tin the wires and then fit heatshrink. Solder together. And shrink. I wanted the sense wire (normally yellow) to run into my case and be plugged into a motherboard header so that I can monitor fan speed in the PSU. I used some Orange braid for this wire. Nothing complicated here, just basically soldered a yellow wire to the redundant Magma fan's sense wire, added the braid and heatshrink. Fully wired up. Fan needed to be fitted back into the PSU cover. Fan MUST have airflow pointing into the PSU. The fan will usually have arrows to help with this. I used the rubber grommets that came with the Magma, inserting the smaller diameter through the case and into the fan grille and eventually fan, like so. I used a pointed nose plier. Fits together pretty nicely. Nice grommets from Enermax. Then basically fit the cover back to the main part of the PSU, fit the screws and put the sticker back on. The job is done. A comparison on visuals. Chuck the crappy 2,400rpm fan away. And fit back into your case. And now for my result. The difference between the 2,400 rpm mounted with screws and this 1,500 rpm mounted with grommets is staggering. At idle, where it's most important to me, the PSU is to all intents and purposes silent with the fan purring away slowly. The air coming out of the back is actually comparable to the airflow I felt before the change, which is odd but yet comforting that the components are still getting cooled. Will update again when I have more data such as temperatures and under load sound signature.
Can I just add that you didn't mention how important it is to take current into consideration when you are choosing the new fan for your PSU... your PSU stock fan had a current draw of 0.45 Amps and the Magma (from memory, correct me if I'm wrong) has about a 0.4 A draw. This is fine because the fan power rail on the PSU main board is being supplied with enough current to run the fan at it's maximum RPM, but some fans require a lot more current than 0.4 Amps and if you fit a fan which requires more than that to a header which can only supply 0.45 Amps then the fan will not operate properly and there's a chance the fan header/power line in the PSU will blow from the strain, not to mention the PSU potentially overheating. Just saying. I do this mod for people regularly when I'm powder coating and/or sleeving PSUs and they sometimes suggest or even provide me with replacement fans that will not work with their PSU because the fan header can't provide enough current to drive them.
That's a valid point Unicorn, thanks. I suppose if someone were doing a mod to increase PSU airflow and installed a faster fan with a high current draw then things could go pear shaped. Going for less current is not a problem though and the fan will take only what it needs. Who knows though the PCB in the PSU could have loads of current available to the fan, possibly even several amps but it's best to be safe with these things. Maybe this is why some people power their PSU fans via motherboard or fan controller.
I've made the mistake of assuming that the power rail for the fan in the PSU can handle any fan before, I installed a SilentX ixtrema fan in a PSU which had a lower rated fan in it before and it just wouldn't spin, so I had to change it. Of course it depends on the PSU, and that was a while ago, on an older, decidedly cheaper PSU than your average Corsair, Enermax or FSP etc. Still, it's better to check. All you need is a multimeter.
