Question How to control multiple LED fan's while having enough power?

Mar 26, 2019
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I just got a 4 way PWM fan splitter for my LED fan's in my case. But now the LED's are blinking? Its slighly annoying and I think Its due to power constraints, So Im wondering is there any way I can fix the blinking, have all 4 fans functioning, and have it be controllable?

Specs: Custom Build 700$ PC
GPU RX 480 8gb
CPU RYZEN 5 1600
Ram 16gb
1 SSD 256 gb
Case Phantakes Eclipse P300
Mobo B450 Pro
PSU Corsair CXM 550+ W 80+ Bronze certified

PSU Is maybe a month old or so I just cleaned the case out after installing fan slitter.
so should be fine
OS: Unactivated Windows 10

fans now seem to be turning on and off every time they blink?


Case fans Thermaltake Riing 12 Series Red High Static Pressure 1x120mm 3x140mm
 
Last edited:

Ralston18

Titan
Moderator
Update your post to include full system hardware specs and OS.

What PSU is installed: make, model, wattage, age, condition?

If the problem is indeed power related (TBD) then you will either need to reduce the current wattage demand or install a higher wattage PSU.
 
Mar 26, 2019
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I fixed the article. I dont know if its power for certan thats affecting it but If it is, is there any possible way I can keep the LED's, fan controllability, and all four fans functioning?
 
It MIGHT be power problem, although the fan specs say it should not be. Any mobo fan header should be able to supply up to 1.0 A to its total load, which is what you are doing if you are connecting four fans to a single header using a Splitter. Now the fans you have show specs of 0.25 A each for the three 140 mm models, and 0.20 A for the 120. That is just barely under the header normal limit, so MAYBE you are trying for too much current from the header.

I am a bit intrigued by your saying you have a 4-output Splitter. They do exist and that really is the only way to connect these 3-pin fans to one header using the older Voltage Control Mode. I just want to be sure we're talking the same thing. A SPLITTER has only two types of "arms" or connections. It has ONE arm that goes to the mobo fan header to get all the power. It has three or more output arms (or headers on a board) to plug your fans into, and that's all. A HUB is a different device with those types of connectors PLUS a third cable that must plug into a SATA or Molex power output from the PSU. You can NOT use a Hub with 3-pin fans normally. So just confirm that you do have a SPLITTER, please.

Unfortunately, the term "B450 Pro" is used for mobos by at least three makers - Gigabyte, MSI and ASRock - so we do not know which you have. Please post back here which maker and exact model number, so we can look up its details and help further.
 
Mar 26, 2019
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I Have a splitter. It has 1 connection to the motherboard and 4 outputs. It does not have a SATA or Molex power output from the PSU.

The motherboard is an MSI B450-M2 motherboard.

Thank you for the quick responses.
 
Thanks for that info. So this should work if you check a couple of points. As you say, you are using a Splitter to connect four 3-pin fans to the only mobo SYS_FAN header. Look in your manual on p.14 for info on configuring that header. Make sure to choose the SYS_FAN header. See the little diagram. At upper left ensure it is set to use DC Mode. The on the graph of RPM (vertical axis I believe) versus Temperature, move the circle at lowest temp / slowest speed up to get it to use a higher MINIMUM speed at low temperatures. This will ensure that the lowest voltage supplied to the fan motor AND the LED's in the frame does not go too low. Too low a voltage can cause the motor to stall AND cause the LED's to fade or quite completely.

See your manual p. 18. To get into BIOS Setup so you can make these adjustments, hold down the "Del" key as soon as you start up your system, until the opening screen of Setup appears. Merely tapping "Del" sometimes gets missed as the busy system starts up. Navigate to the screens for configuring the SYS_FAN header, then adjust as above. When done, use the F10 key to get out of Setup and be sure it SAVES your new settings.
 

Karadjgne

Titan
Herald
Not gonna work. Theory yes, but not for 4x DC powered fans on the same header unless all 4 fans pull less than @ 0.2A. In theory each header is rated at 1A, but resistance in the wire changes that total if you want to try and maintain the voltages. For 4x fans use 0.8A, for 3x fans use 0.9A as max.
Most led fans are 0.3A and higher since the leds and fan motors are pulled from the same power source. Generally, unless it's a very good led fan, with uber efficient motor, you'll not get more than 3x DC fans on 1 header.

Leds require a certain amount of voltage to run, lower the voltage, dimmer the led becomes until it gets too low, then you get issues. Depending on the leds, this can be 5v ,7v ,9v or even full 12v.
 

Karadjgne

Titan
Herald
Yes. Those TT fans are rated at 2.4w (0.2A). So use 3x 140mm on the splitter and 1x 120mm to the sys_fan header closest to the rear exhaust (assuming that's where the 120mm is). Then only thing you'll need to do is locate the one fan lead that contains 4 wires (the other 3 will have just 3 wires) and make sure it's connected to one of the fans. Bury the 4th connector, it's not used.

That'll put 0.6A on one header, and 0.2A on another. The fans will be controlled by bios anyways.
 

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