Tutorial: Swap the fan on a PSU.

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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. :D

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 1,00 rpm and suspended hard drives inside an insulated Antec P183.

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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. Perfect.

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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.

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The stock fan.
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The power regulators -- basically this is what needs cooling (hence the big heatsink)
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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. :D

First thing first let's identify and understand the wiring.
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A normal fan connector.
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And a modded Magma connector.
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So cut the wire and mark as appropriate.
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Bare and tin the wires and then fit heatshrink. Solder together.
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And shrink.
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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.

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Fully wired up.
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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.

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Then basically fit the cover back to the main part of the PSU, fit the screws and put the sticker back on.

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The job is done.
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A comparison on visuals.
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Chuck the crappy 2,400rpm fan away.
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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.
 
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230v isn't "lethal"! :D ;)

This monster capacitor must hold a joule or two when energised. I wouldn't want that energy dumped through my heart whether it be DC 12v or AC 230V.
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W3bbo said:
Personally, I would go for a fan with high cfm as airflow is impeeded in such a cramped environment.

Well the FSP Aurum isn't really all that cramped and also high airflow = high noise which kind of defeats the point of the mod.

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Clearly there's always a risk that the unit could now overheat with a 900 rpm drop in rotation speed but a 2,400 rpm fan, no matter who makes it will always be hellish noisy in my opinion.
 
Well I modded a OCZ/FSP 600W 80% efficient PSU (stock 2000 rpm) with a 1600 rpm fan and it was just fine after two years of heavy use, running just as cool as before. That wasn't bristling with heatsinks either.

As I said these types of PSU are designed to act as a system exhaust as well as to cool their own components. I wouldn't go passive on this PSU though.


KD - I thought the Magma was more red than orange but now that you mention it... :)
 
Just wanted to add that everything is still working just fine after 8 months of operation. The fan never goes up to more than 1100 rpm, even under heavy BF3 loading, which is the most my PC gets as I don't run benchmarks or rubbish like that.
 
According to a review the fan in the Joule (nice name for a PSU) 1000W seems to be a 0.45A sleeve bearing job so I'd expect that to be fairly fast spinning. The Xigmatek orange is only 1500 rpm so you may run into heat problems, especially if the stock fan is a near 3,000 rpm model. If you can load it up to your maximum watch for temperature differences between intake and outtake, or even get a temperature sensor inside the PSU.
 
+1. i'm surprised you didn't sneak some LED's in :p

I probably would have done if my PSU didn't reside in the lower compartment of my P183, which considering the unholy mess of cables down there, I'd rather not have lit in glorious orange. Still an opportunity missed.

Could even have had a LED readout on the side showing internal temperature.
 
That orange does look really nice Kiiyzoo. Nice job there mate.

@Abz- A three pin fan is basically a two pin fan with an additional sensor that has a signal down the third wire. The motherboard uses this to determine speed.

A four pin fan is similar again but has a few additional components to allow fast switching on and off, the signal for which comes down the fourth wire.
 
It's fortunate the motherboards don't really care about the fact there's no fan taking current from the fan header yet still reports the speed. Maybe some motherboards have some kind of preventative measure that allows the sense circuits to be utlised like this but happily mine isn't one of them.

It's also true that the sensor will require a circuit to operate and it just wouldn't work if the PSU fan wasn't itself grounded by it's black wire direct to the PSU. If I was to remove the fan and create a different ground potential using +12v as ground and +24v as live it might totally mess with the sensor, but I'm not going to do that.
 
Someone mentioned an Akasa Apache in another thread, but that is a 4 pin PWM, so not sure how I would wire it up. Are there any decent 3 pin 140mm fans?

Depends on the PSU (and whether it has a connector for the fan or not) but you'd only wire up the red and black wires anyway. You'd lose the PWM of the fan but it'll just operate like any DC fan.

I'd say an Apache would be a decent choice beccause it has highish airflow and a hydro bearing. Had a quick look on OcUK for fans and the majority of 140mm fans seem to be slower spinners.
 
just like you extended the rpm wire, couldnt the rpm and pwm wire be extended to the motheboard to run the pwm function too? :)

They could both be extended but that would totally mess up the fan control as you'd then have a mismatch of DC control by the PSU and PWM control by the motherboard, and besides the PWM would then not be related to the temperature/workload of the PSU.
 
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