Power Supply fan replacement

my current power supply is a "LC Power Green something 550W" with a 140mm fan. While that sounded great on paper (140mm should be silent, eh?!) ... it's not. It's already quite notable in idle, shortly after system starts and it stays at that noise level. Which means it's obviously one of those power supplies that never get really loud, but are always at the same noise level, no matter how the power output.

I've installed it in my NZXT H2 case with the fan pointing to the case bottom, where it takes in cold air and pushes it out to the back of the case. Which means the airflow is not interacting with the case at all. The air coming out at the back is almost "freezing cold" at all times (idle/load). which is good, ofc. But also indicates that the fan is doing way more than it needs to do.

Anyway, since it's by far the loudest component left in the case, I want to replace the fan with another one.

The question(s) coming up is/are the following:

1.) Should I solder the new fan onto the cables of the old one or is it possible to run the new fan via a 3/4 pin connecter from the power supply like a case fan?

>>> I have no problem with soldering, however, I think that way the power supply will try to regulate the speed of the new fan, which is not exactly what I'd prefer it to do. I intend to use a high airflow low RPM fan running at max RPM all the time (e.g. Enermax T.B. Silence 750 RPM, 77 m³/h) or if that is not enough (is it?!?) a max 154 m³/h fan regulated by a fan controller.

2.) Is there a way to slow down the actual fan to run at lower RPM? Maybe add a regulator like some case fans (e.g. T.B.Silence-Manual) have.

I have not opened the power supply yet, so I don't know yet how many pins/wires the old fan is using, which might be of interest for the soldering solution (PWM?!? or maybe not, not sure).
Also note that the max load of my PC is <200W, which is quite a bit less than half the capacity of the power supply.

PS: I know about the capacitors discharging risk and all, I know about warranty being gone, etc. so please don't tell me about that.
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  1. Why not return the PSU and get a better (quieter) one?

    Use of a normal fan connector (3 or 4 pin) is not recommended.

    If you are going to "break the seal" on the PSU, then just solder in properly. The proposed Enermax fan should be fine given your setup.

    Good luck and BE CAREFUL!
  2. COLGeek said:
    Why not return the PSU and get a better (quieter) one?

    Well I can't return it unless it's broken, which it is not (I have it for about 2 month now).


    Use of a normal fan connector (3 or 4 pin) is not recommended.

    Just curious, if you maybe can elaborate the reason behind that a little more?

    Thanks for the help. :)
  3. Do you really want a wire extending out of your PSU? Also, the PSU won't detect a fan and may not operate at all.
  4. Not running at all might be an issue which I thought about, too. On the other hand it is possible that it doesn't "check" the fan, but purely relies on temperature values provided by it's sensors as long as they are fine it might just work.

    The "wire" would not be an issue since the case has a "double" back which provides really awesome cable management and there are some wires coming out of a PSU, by nature. :D

    As a side note: I'm running a 120mm case fan on my HD6770 instead of it's default fan, just fine and it doesn't care about the fan not being connected to it.

    Well, seems like I have to try that out to find it out, or forget about it. I was just hoping someone tried that before. Thanks again. :)
  5. I had a fan fail on my power supply recently, and since I did some wire mods I couldn't RMA the psu. So, instead of spending 200 bucks on an AX850, I put in a new fan.

    Yours might be different than mine, I'v got an OCZ 700w Fatal1ty (non-modular). When I cracked it open the fan was attached by a 2 wire header. When dealing with fans this is what the wires do.

    Red - Voltage
    Black - Ground
    Yellow - RPM Monitor
    Blue - Pulse Width Modulation

    Typically, that is.

    So I cut the cable off the old fan so I could use the 2 pin connector. I didn't want to cut my new fan, so I took a 3-4pin adapter and cut off the male 3 pin section. I then soldered those cables together. Now, I can put any fan in my PSU that has a 3 pin connector on it.

    The PSU will still control the fan speed base on temp, by adjusting the voltage, but it would be good to get a high quality quiet fan. I tossed in a Noctua, it's silent and works beautifully.
  6. Nice approach, thanks a lot for sharing. Do you remember which fan exactly? I suppose it's one of the 120mm Nocuta fans?

    I'm currently using T.B. Silence fans in my case and I'm really happy with them.

    Enermax has only one 140mm T.B. fan with fixed RPM (750RPM @74 m³/h), not sure what would be best for the power supply to handle.

    e.g. a fan with a higher max RPM/more RPM "range" or if that doesn't matter at all as long as the max airflow is alright.
  7. I used the NF-P12 in my PSU, it has higher static pressure than the S12. I used the NF-S12B FLX for the rest of my chassis, on my CHIV's fan controller. I've spent the last couple years trying to find cheaper fans that are better, and some are really quiet at first, but about a year in the bearings go. I had that one NF-P12 and it just keeps on rolling dead silent. I'd love to know if your TB Silence hold up, but chances are, with a 6 year warranty I won't be buying fans anytime soon. :D

    They have the 140mm version, here:


    Although the fan chassis looks weird, it should still have the same mounting holes.
  8. Most power supply fans are fitted onto a two way connector or soldered straight into the board. You can get thermally controlled fans which would make a low noise replacement. I would be cautious about reducing the air flow through a power supply to much as some of the power supply components get very hot and rely on the air flow to cool them.

    Caution the big capacitors on the power supply can retain their charge for a long time and can give you a nasty shock. When resembling the power supply make sure that the insulating layer is fitted under the PC board and side of the case is fitted back correctly.
  9. I think I'll settle with a Prolimatech Blue Vortex Blue Wings 140mm fan and just try out dannoddd's method.

    18,1 dB(A), 1.100 RPM, 145,8 m³/h ... sounds quite nice and seems better suited for the power supply than the 140mm, 15 dbA 750 RPM, 77,13 m³/h T.B. Silence counterpart. :)

    I just hope that there is a 2 pin connector, guess it's time to take a look. :D

    I'm aware of airflow and air pressure. Sometimes pressure might be important and that normally only comes through higher RPM and/or a specific layout. Some fans spread the air more than others. However due to the power supply only having 2 openings, one at the back and one at the bottom where the fan sits, it's quite a tunnel effect, so pressure shouldn't be all that important to get the air flowing out through the back.

    I'm very pleased with Enermax T.B. Silence fans.

    1x 80mm fixed RPM (CPU fan) idle 40°, ~56° load
    3x 120mm fixed RPM (case fans, 2x intake front, 1x exhaust back) @70%
    1x 120mm manual speed (GPU fan) GPU idles @40°, ~65° on load
    1x 140mm fixed RPM (case fan, top exhaust) @100%

    All I can say is, that there is a slight whisper if you are directly aside the case, due to the airflow in the case, but it's impossible to locate a specific fan. If anything the manual controlled one, because I want my GPU to be on less than 70° on load. :)

    All those fans have quite remarkable airflow, while running at low to medium RPM by default and are listed between 12 and 16dbA @max speed. They have detachable blades (can be cleaned easily) and are way less expansive than Noctua.
  10. So a little update on the topic.

    Like planned I got a Prolimatech Blue Vortex Blue Wings 140mm (the blue LED version). I opened up the power supply and cut off the old 140mm fan. It had a red and black wire, which made things easy to track. The new fan came with a 3pin to 4pin adapter. I removed the 4pin side, smoldered the 3pin connector on the old fans red and black wires connected to the power supply and the job was done. Took me about 20minutes overall. I didn't even remove the power supply from the case, just turned it around and plugged of the mainboard and HDDs power connectors. I can now easily replace the fan, if needed, later.

    The new fan runs really quiet. The only "noise" left in the case is the airflow when I have all fans @100% speed. The blue light coming out of the back of the case looks pretty nice, too.

    *happy end* :bounce:
  11. I hope that you fitted the fan the right way around, it can be fatal to the computer if this is wrong, I use a bit of paper to check the air flow direction. I have on more than one occasion fitted the fan the wrong way around.
  12. Hehe, thanks but that never happened to me. There's actually just one direction for about every fan I had so far and that I know of.

    They all blow air from the "completely open" (top side fan blades) side through the side where the fan is attached to it's encasing (bottom side fan blades). :)

    In case of a bottom mounted power supply with the fan facing to the bottom of the case, that means it is supposed to suck in air, blow it through the power supply and out of the back of the case.
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