How do I undervolt a Delta fan?

T

Trackr

[H]ard|Gawd
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Feb 10, 2011
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I have a 120mm Delta fan and it's far too loud for conventional use.

I've heard that you can undervolt them, but I'm not finding any posts about it..

Is it possible? The fan won't start at 5v.. :(
 
Starting voltage is usually higher than operating voltage. I use a fan controller, but make sure you get one that can handle the draw from the delta.

I'd look at 25-30w per channel fan controllers.

I do have another delta that has a 4 pin pwm connector attached to a motherboard and that works pretty well, although it doesn't let me turn it down as far as the fan controller.
 
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I don't fully understand.

Okay, the +12v stays the same. So +12v to +12v.

Now, I switch the 12v Ground with the +5v so that the Ground wire is actually +5v?

If it's getts +5v on the Ground.. how does that work?
 
If you ever bought a Noctua fan or know somebody that has one chances are they are not using their reducers.
It's a quick and easy way but only if it's a 3 or 4 pin, not molex.
 
In a DC system as we are look at here, there is no ground. All equipment is driven by the potential between the supply wire and the return wire. All that is happening here is changing the return to a higher value. 12-5=7 volts. You could overclock your fan by changing your 'ground' to say the -12V lead coming from your power supply. This would end up with 24V to your fan (and would release the magic blue smoke making it not work anymore)
 
Trackr said:
I don't fully understand.

Okay, the +12v stays the same. So +12v to +12v.

Now, I switch the 12v Ground with the +5v so that the Ground wire is actually +5v?

If it's getts +5v on the Ground.. how does that work?
Click to expand...

Its complicated. The basic idea is that it will feed the difference in voltage to the fan. 12-5 = 7V. It works, people have been using this trick on molex plugs for ages.
 
Okay, so can I just splice the Ground to the +5v? I'll try it later today and write back. Very interesting idea.
 
jmilcher said:
Its complicated. The basic idea is that it will feed the difference in voltage to the fan. 12-5 = 7V. It works, people have been using this trick on molex plugs for ages.
Click to expand...

Its what I do. Works great, although I did have one power supply (BFG 800w) that would refuse to turn on when doing 7v molex mod.

Expect that Delta to click and grind when under volted though.
 
Just wanted to let you guys know that it DIDN'T work.

I managed to 7v a regular fan (worked well).

But when I tried to 7v my Delta, the PSU shut down.

I damn near thought I fried it, but thankfully I managed to turn it back on.

I tried again, and the same thing happened. Now what am I supposed to do? This thing is as loud as all outdoors!
 
Could be a few things, There needs to be a load on the 5V line for this to work. it also could be a regulator on your PS. Not enuf info in your sig to sort it out. The easiest solution is to get a fan controller then you can fine tune what speed you want.
 
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