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post #4 of (permalink) Old 05-26-2014, 05:33 AM - Thread Starter
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PWM Fan Independent Speed Curve
PWM fan rpm is not a fixed ratio or percentage of PWM signal. The PWM signal to rpm is part of the programming in PWM circuitry built into each PWM fan.
Here are some examples. Black graph line (top line in chart) is fan rpm; PWM % is shown across bottom of chart. Notice how all of these fans are flat-lining at idle at different minimum fan RPM. PWM% signals below this minimum fan RPM have no effect on fan. Also notice how the PWM% to rpm is not a the same progression for each fan .. it is not a linear progression, but is instead a custom progression that is programmed into each fan's internal PWM circuit.

All graphs are from Thermalbench.com fan tests and reviews.

Normal PWM Splitter with PSU Power & Auxiliary RPM Plugs

How to Monitor RPM of Fans on Splitters & Hubs

Controlling case fans with PWM signal from motherboard CPU fan header and GPU fan header.

There are some limitations:
  • Obviously motherboard and GPU must have PWM
  • Obviously fans must be PWM
  • Motherboard can only support 8-9 fans (PWM signal strength gets too weak)
  • No idea how many fans GPU can support.
Setting up motherboard PWM control of PWM case fans:
  • Use a PWM splitter with molex/sata connector. Gelid and Swiftech are my preferred. I do not use Akasa PWM splitters because their wire temination into connectors is very poorly designed. Look at one and you will notice all wire distribution is at the connector .. all flex and load is at connector .. while ones like Gelid have cable distribution away form the connectors.

  • Plug PWM splitter to motherboard CPU fan header and PSU
  • Use CPU cooler fan as "master" fan. This is the fan that sends rpm signal to motherboard PWM header.
  • Additional CPU cooler fans and case fans will ramp u and down with CPU fan.
  • Can use a second PWM splitter on 3-way & 4-way PWM splitter.
  • Setup fan speed curve with motherboard bios or software. Gigabyte has EasyTune 6 and Asus has SmartFan. I set minimum at 30% fan @ 30c and maximum at 100% @ 65c. Than watch temps and see if you want more or less rpm to keep temperature and noise where you want them. My sig rig idles 24-29c @ 700rpm; 100% all cores is 42-48c :950-1050rpm.
Setting up GPU PWM control of case fans:
  • Obviously GPU fans need to be PWM. Because the GPU PWM header/plug is smaller than normal PWM we need a Mini 4-Pin GPU (Female) to Mini 4-Pin GPU (Male) / 4-Pin Fan (Male) Cable Splitter Adapter is needed-. The blue wire going to normal PWM socket needs to be cut off of mini PWM plug. (You can use this wire to monitor rpm on case fan by connecting it to a normal 3pin fan plug in the rpm position.) Plug a PWM splitter into the normal PWM socket and PSU for case fans.

  • Case fans hooked onto this splitter will ramp up and down with GPU fans.
  • Use GPU software or Bios to setup fan speed curve

modDIY has several adapters and splitters for this.
mini 4-pin PWM adapters

Mini 5-pin PWM adapters

GPU PWM to Normal PWM Splitter with PSU Power & Auxiliary RPM Plug

modDIY has several adapters and splitters for this.
mini 4-pin PWM adapters
Mini 4-Pin GPU (Female) to Mini 4-Pin GPU (Male) / 4-Pin Fan (Male) Cable Splitter


And many more.

Mini 5-pin PWM adapters
5-Pin VGA PWM Mini PH Connector to Dual PH Mini 4-Pin Fan Cable Splitter


5-Pin VGA PWM Mini PH Connector to Dual PWM 4-Pin Fan Cable Splitter

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Phanteks Owners Club Ways to Better Cooling
i7 980 @ 3.55GHz =PH-TC14PE w/2x TY-143 fans =Crucial Ballistix 3x4GB =GA-X58A-UD5 =ASUS GTX580 DirectCU II =Enermax Modu84+ =Define R2 w/3x TY-140 case intake fans; all PWM controlled by CPU fan socketPhanteks Enthoo Primo MoBo Rampage III Extreme CPUi7 980X
@ 4.0GHz =R1 Ultimate w/2x TY-143 fans =Dominator GT 6x2GB =Rampage III Extreme =ASUS GTX580 DirectCU II =TX850 =Enthoo Primo w/ custom castor base

Last edited by doyll; 05-02-2018 at 07:17 AM.
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