Does anyone know if it is possible to 7volt the psu fan?
I know how to 7 volt a normal case fan with the 4 pin connector, but inside the psu, I only have 2 leads, which I assume one is 12V and the other is ground. So it doesn't seem possible to lower its speed by reducing its voltage.
I would just simply replace the fan, but it is a matx psu and it uses a low profile fan, which for me is rather difficult to come by.
So am I SOL or is there something I can do about it?
One last way of reducing the speed is using resistors, but I'm sort of afraid as I was hoping for something simple. I guess my main concern is having extra stuff in the already small psu, especially resistors. Am I just being paranoid or should I really be concerned?
But if I was to try using resistors, how do I know how much resistance do I need to add. The fan uses 0.2A according to the label and I'm to reduce it to something less than 7V.
Any comments is much appreciated,
thanks
newbie need help 7volting psu fan
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you can run wires out to the case but it's not a neat solution. you will probably need soldering iron to do a nicer job..
inside the PSU there is a high voltage section and a low voltage section, the low voltage side of the pcb is where the mass of DC wires comes out from. almost always, yellow wires are 12V red wires are 5V and black is GND. in stock form the fan will be connected with + on 12V and - on GND, sometimes by a little plug and sometimes, usually on cheaper boards, just wired onto the pcb. for 7V you want to disconnect fan and wire it between 12V and 5V (i.e. find a red section on the board and solder the GND wire there). i don't like 7V, so personally i prefer to put + to 5V and - to GND when i do this kind of job.
to rewire the fan in the low voltage section you have several options. cutting into the DC wires and making a tri-joint there should be your last ditch effort. the 5V section you need is where the red wires go to, usually it's all clumped up in a big 5V blob and most of the time you can find a little vacant wire hole somewhere in the 5V blob, already waiting there for you. then you can just strip the wire and poke it through, solder on the underneath of the board and you're done. seldom there is no hole or sometimes there is a hole but it's been washed over in the solder bath, then you can just dig a new hole by hand using a very fine drill bit. on very rare occasions there is no room to even drill in a hole, then as a last resort you can just tap into a [red] wire (i only say it's a last resort because it's the hardest / takes most time and effort. the electrons don't mind).
i probably made it sound harder than it really is, it's quite a simple job.
inside the PSU there is a high voltage section and a low voltage section, the low voltage side of the pcb is where the mass of DC wires comes out from. almost always, yellow wires are 12V red wires are 5V and black is GND. in stock form the fan will be connected with + on 12V and - on GND, sometimes by a little plug and sometimes, usually on cheaper boards, just wired onto the pcb. for 7V you want to disconnect fan and wire it between 12V and 5V (i.e. find a red section on the board and solder the GND wire there). i don't like 7V, so personally i prefer to put + to 5V and - to GND when i do this kind of job.
to rewire the fan in the low voltage section you have several options. cutting into the DC wires and making a tri-joint there should be your last ditch effort. the 5V section you need is where the red wires go to, usually it's all clumped up in a big 5V blob and most of the time you can find a little vacant wire hole somewhere in the 5V blob, already waiting there for you. then you can just strip the wire and poke it through, solder on the underneath of the board and you're done. seldom there is no hole or sometimes there is a hole but it's been washed over in the solder bath, then you can just dig a new hole by hand using a very fine drill bit. on very rare occasions there is no room to even drill in a hole, then as a last resort you can just tap into a [red] wire (i only say it's a last resort because it's the hardest / takes most time and effort. the electrons don't mind).
i probably made it sound harder than it really is, it's quite a simple job.
I'd make sure the PSU was cool enough at 5V or 7V before a broke out the soldering iron, especially with an MATX. I sure wish life had an "undo" button like AutoCAD does. 
Last edited by threevok on Mon Dec 20, 2004 9:50 am, edited 1 time in total.
thanks for the suggestions and I have now routed the fan out of the psu
now my question is, how would I know if the psu is cool enough or not.
i dont have a thermal sensor on the motherboard, so I'm not sure how I can accurately check the temperature in the psu.
With the fan running at 5V, my case temp would stay under 50C and my processor (still running at 12V) stayed under 45C under 100% load
is this ok? should I be concerned about the heat in the psu?
now my question is, how would I know if the psu is cool enough or not.
i dont have a thermal sensor on the motherboard, so I'm not sure how I can accurately check the temperature in the psu.
With the fan running at 5V, my case temp would stay under 50C and my processor (still running at 12V) stayed under 45C under 100% load
is this ok? should I be concerned about the heat in the psu?
