[SOLVED] How many ARGB fans can I plug into JRAINBOW motherboard slot?

[victormunro]

Hello, I am having a really terrible time understanding how I could find out how many ARGB fans I can plug into the JRAINBOW motherboard slot. The math confuses me and I do not want to take the chances of frying that JRAINBOW port. I heard that's what happens when you overload it and I really do not want to do that with my new computer I just built a couple days ago.

I have the MSI MPG B550 Gaming Edge Wifi, here's the manual and in Page 42 is where it talks about the ARGB and where it tells you the voltages and all that.
Here is the 4 ARGB fans that I have daisy chained into JRAINBOW1.

 

[Karadjgne]

The pwm signal from the jrainbow header will support upto 10 argb fans unassisted. Assisted by powered hubs like the Corsair Commander series, you can have upto 72 argb fans in daisy chained hubs

But that's just argb. Got nothing to do with the fans themselves. Argb and fan is 2 different things. Fans are generally 12v and argb is 5v. 2 different sources, so consider them seperate things. Fan and light.

Most headers can handle upto 1A worth of Fan. If your fans are less than 0.2A each, you can have upto 5 Fans. If your Fans are more than 0.5A each, you can have 1 Fan per header.

It's not really the argb that sucks up the header, it's the fan motor, the limit of 10 argb is due to the pwm signal strength getting split up so many times.

When talking about the argb voltages as such, that's intended for strip lighting, each led uses a certain amount of amperage, so a strip can contain only X amount of leds and not overload the jrainbow header. A strip with 40 leds will use more amperage than a strip with 20 leds, so if the header will support 40 leds, you could use 2x strips of 20 instead.

Conversely, if the header supports upto 1A worth of leds at 5v, and each led individually is 0.02A, you can have strips of a maximum of 50 leds total in daisy chain, but if using super brights that use 0.03A then you'd be limited to strips with upto 33 leds.

 

[Paperdoc]

As Karadjne above points out, fan MOTORS and fan LIGHTS are two completely separate things. Each fan unit has TWO cables, one for each. Since OP has asked specifically about the JRAINBOW headers, this concerns ONLY the LIGHTING parts. (Incidentally, the signals on these lighting headers are not PWM signals.)

Your manual on p. 42 says each JRAINBOW header can support up to 75 LED's, or 3.0 A current load. IF one cannot find the amps load rating of a lighting device, it CAN be estimated from the rough guideline that one LED can consume up to 0.020 A (20 mA). The Phanteks web page for those fans says each fan contains 12 LED's, but MORE importantly DOES tell you each fan's lights can consume up to 0.36 A. From that, 3.0 A max load can support up to 3.0/0.36 = 8 fans of this type. So that's the limit of a daisy chain connected to ONE JRAINBOW header. Same for the second header.

OP, a similar consideration should be made of max load connected to a FAN header on your mobo. Most mobo headers for FAN MOTORS can supply up to 1.0 A per header, and that applies to the SYS_FAN headers on your mobo. Fan specs normally should include the max current load of the MOTOR separately from the lights. For yours, the max current load per fan motor is NOT given on its web page, so we must rely on the guideline that such motors typically consume from 0.1 to 0.2 A max each motor (and typically closer to the 0.1 A point). Use that to calculate the max number of fan MOTORS you can connect to EACH mobo fan header.

 

[Karadjgne]

The signal sent to the argb controller chip for each individual led is a pwm signal. Each chip is addressed, not the specific led. The led itself contains 3 or 4 (argbw) diodes and the pwm signal sent to the chip address contains the instructions for the chip. Each led is still standard rgb, still amperage split, but the chip decides the spilt for that particular led, instead of standard rgb where the split is decided to the whole line from 3 master diodes operating upto a specific amperage.

When you see purple, that means amperage is split between the red and blue diodes and green is blocked. It's why standard argb cannot do certain colors such as bright white or brown, that being higher amperage than the chip allows or tertiary colors containing multiple shades in a single diode.

But that's getting seriously technical.

 

[Paperdoc]

I agree with almost everything Karadjne says above. It's just that the digital control signal in an ARGB system is not PWM. Technical nit-picking, to be sure.

The speed control signal for 4-pin FANS is a PWM signal. That stands for Pulse Width Modulation. This signal type is very like a "square wave" in that it is either fully on or fully off, and for computer fans the Voltages are either 5 VDC or zero; the signal frequency is typically 20 to 22 kHz. For a square wave it is ALWAYS on 50% of the time, and off 50%. For a PWM signal, the % On time is what varies, from 0% to 100%, and that is the nature of the information it carries. In a 4-pin PWM system fan, the fan has a small chip inside the case that uses this signal to switch on and off the flow of current from the fixed 12 VDC supply line (Pin #2) through the motor windings in the same pattern so this produces rapidly-surging pulses of torque, and thus of motor speed. A PWM signal is kind of half-way between digital and analog. It is binary digital in the sense that it can contain only two states, on or off. But it is analog in the sense that the % On value is continuously variable, and there is no digitally-coded value in its information.

My understanding of the control signals in an ARGB system is that they are a stream of digital data packets. Each packet contains a Node address and three intensity or amplitude specifications, one for each of the three basic LED's in one Node of the lighting strip. The controller chip in each Node listens to all the packets on the control line but responds only to the ones with its address, using those three amplitude settings for its own group of three LED's. This is truly a digital data packet information system.

OP, sorry but this is NOT part of what you asked for help with. Just a side discussion. And thank you for Best Solution.