PWM Splitter 3&4 pin

Josh P

Josh P

Josh P

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Joined
29 Sep 2009
Posts
861
Location
Cambs, UK
Hi,

I've currently got 3 Akasa Apache 4-pin fans running from one motherboard header (CPU_FAN) using the Akasa splitter. They get their power from a molex direct from the PSU. If I were to daisy chain these splitters, could I also attach some normal 3-pin fans to them? I realise they will get the full 12V, but is it allowed? :p
 
it is but the more you add the slower the fans wil go. The reason being is the PSu will always only pump out a certain amount of power per link. To get the most out of the fans i suggest you set them up on there seperate 12v rails or just stick with the ones on the mobo.
 
A molex line is quite capable of running silly numbers of fans before the voltage drops enough for anyone to notice. The fans are in parallel if that helps, assuming perfect supply they'd all get 12V. Doing it through the pwm splitter is a bit odd, as like you say, the 3 pin ones will run at 12V. Normally people just use a 3 pin to molex adapter directly.

However yeah, you can daisy chain loads of these together, and run any mix of 4 pin pwm at variable speed and 3 pin's at 12V you wish. Google "InLine Multi Power Fan Port (12x)" for a good alternative.
 
Last edited:
JonJ678 said:
A molex line is quite capable if running silly numbers of fans before the voltage drops enough for anyone to notice. The fans are in parallel if that helps, assuming perfect supply they'd all get 12V. Doing it through the pwm splitter is a bit odd, as like you say, the 3 pin ones will run at 12V. Normally people just use a 3 pin to molex adapter directly.

However yeah, you can daisy chain loads of these together, and run any mix of 4 pin pwm at variable speed and 3 pin's at 12V you wish. Google "InLine Multi Power Fan Port (12x)" for a good alternative.
Click to expand...

I use one of these to hook afew PWM fans to the same motherboard header.

http://www.overclockers.co.uk/showproduct.php?prodid=CB-031-AK
 
Which is a good approach Parsley, something I'd like to do, and what the OP is currently doing. The question was whether a few of these daisy chained could run normal 3 pin fans, accepting that they'll run flat out rather than at lower speed. The 4 pin fans will still run at variable speeds.

Wipster is correct in that putting lots of fans on a motherboard header is hazardous. However in this case, the cable linked above and in use by the OP, avoids this issue by drawing power from a molex plug instead of from the motherboard. So any number of fans can be run from one header quite safely as long as this cable or an equivalent is used.

Brilliant invention, I only wish I had pwm fans.
 
Thanks everyone,

Jon - that looks like an interesting bit of kit. The reason I asked was partly just to try and minimise the number of cables I had coming off the motherboard, but without having to mess around with a fan controller. I may do some experimenting when my case arrives.
 
Josh Pencheon said:
Hi,

I've currently got 3 Akasa Apache 4-pin fans running from one motherboard header (CPU_FAN) using the Akasa splitter. They get their power from a molex direct from the PSU. If I were to daisy chain these splitters, could I also attach some normal 3-pin fans to them? I realise they will get the full 12V, but is it allowed? :p
Click to expand...

Yes i do this i have 2 splitters controlling 4 PWM fans and one 3 pin which runs at 12v constant. You just connect the Cpu fan of the first splitter to the motherboard connector on the second. You do end up with a lot of wires though...
 
i've got 9 apaches running off the CPU_FAN header; all spin upto ~1460RPM, these all run off the akasa pwm splitter with molex connectors. i've done a bit of soldering to set it up.

i'm sure i could run 18 odd fans off this one header before fan max RPM dropped below 1200RPM :)

EDIT:

MOOGLEYS said:
You do end up with a lot of wires though...
Click to expand...

you do indeed :D
 
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