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5v aRGB daisy chaining? Can i do this?

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Helgaiden

Member
Joined
Jul 14, 2003
So I'm still waiting on some parts to come in so i can't power on and fully test, but before i even connect things i've been trying to work out the math so i can be totally sure and not fry anything.I have a Gigabyte Aorus X570 Elite motherboard which has 2 5v aRGB headers and a kit of some Swiftech watercooling gear and fans.

Thats 6x of the Helix 120 Iris fans which have 18 LEDs each. Each fan also has a daisy-chain connector for the RGB to connect to another fan, and the PWM connector is separate. So my issue is regarding just the LEDs since i can figure that out separately. The waterblock included with their Boreas kit also has 6 RGB LEDs as well, and so does the pump/res combo unit. So i'm looking at about 120 LEDs total.

Their kit includes a controller hub powered by a SATA power connector where all the fans and RGB connectors can connect to, but to change the colors i would have to open the case to reach in and push the button on this controller. No motherboard control. So i ordered their MB Link adapter that lets you connect their RGB connectors to the motherboard for software control. Well that adapter only has 3 RGB headers. But wait, each fan has a daisy chain connector for the RGB, so i can just keep connecting things via those since the MB link adapter doesn't have enough connections. I know they do this to keep you from connecting too many things and frying your stuff, so they don't recommend daisy chaining. I get it. They can't assume everyone has a header that can push alot of power safely.

So with that said, the motherboard's header according to the manual states that it can push 5 amps (it also says 1000 LEDs but gigabyte support eventually told me to ignore that number, and that its all about not exceeding the amp rating of the header). Asking Swiftech how much power the LEDs on their fans use, they didn't really have an answer. So i asked them the model of LED they use so i can research it myself and they told me they believe they are ws2812 leds which use a max current of 20 mA which equals 0.02 Amps.

So it should be simple right? 5 amps max output from header is available. Swiftech Iris MB link gives me 3 connectors. I connect 3 fans (just the RGB) that each fan has an additional fan connected to it, then lastly the waterblock that has 6 LEDs to that second set of fans, and also the resevoir that has 6 LEDs to that second set of fans.

That is
6 Fans at 18 LEDs each, totaling .36 Amp draw per fan totaling 2.16 Amps across all fans
1 waterblock at 6 LEDs totaling .12 Amps
1 pump/res at 6 LEDs (RGB connector separate) totaling .12 Amps

Resulting in total amp draw of everything daisy chained then connected to a single header of: 2.4 Amps

is that right? is it that simple or am i missing anything? Do i need to worry about voltage drop or anything like that? Am i at any risk? Thanks and sorry for the long post, trying to include as much detail as possible.


links in case you guys wanted to crosscheck anything:

WS2812 LEDs: https://cdn-shop.adafruit.com/datasheets/WS2812.pdf
Swiftech Boreas kit: http://www.swiftech.com/boreas.aspx
Swiftech Iris MB Link: http://www.swiftech.com/iris-mblink.aspx
Iris Eco V2 controller (included with the Boreas kit): http://www.swiftech.com/iris-eco.aspx

Appreciate any feedback, thanks.
 

UltraTaco

Member
Joined
Oct 28, 2017
Looks about right:shrug: don't forget that you will see max amp draw if you run all leds white. They dont draw max amp when going through color rainbow pattern or running certain color. When you have white, it will turn on all diodes inside(red green and blue), which in turn makeswhite, hence max rated draw.,

Besides, you can always just split the load if worried. Allou have to separate is the power source. Signal stays the same.
 
OP
Helgaiden

Helgaiden

Member
Joined
Jul 14, 2003
Looks about right:shrug: don't forget that you will see max amp draw if you run all leds white. They dont draw max amp when going through color rainbow pattern or running certain color. When you have white, it will turn on all diodes inside(red green and blue), which in turn makeswhite, hence max rated draw.,

Besides, you can always just split the load if worried. Allou have to separate is the power source. Signal stays the same.


How would i split the power source with the items i'll be using? Its all linked above. As far white goes, are you sure that thats how the LED is working not just using a different shade of blue thru a yellow filter/coating? The LED specs are also linked above.

Assuming they make white by the method you described, it shows that the max amp draw of each LED is 20mA for each color. So then all white would generate 60mA per LED? if thats so, then that would result in 7.2A total current draw if i make them all white.
 

UltraTaco

Member
Joined
Oct 28, 2017
To split power source, you'll likely need to do some soldering.
To generate white, on my rgb strip, I can see super tiny diodes that all light up together, red green and blue. I measured maximum draw when running white color. When I have purple, green, or some other pwm pattern, current drops dramatically. I'm pretty sure they state maximum rated current that led will pull.

Try looking super closely at your leds and see if you can spot individual colors. They will look slightly offset when they light up.
 
OP
Helgaiden

Helgaiden

Member
Joined
Jul 14, 2003
To split power source, you'll likely need to do some soldering.
To generate white, on my rgb strip, I can see super tiny diodes that all light up together, red green and blue. I measured maximum draw when running white color. When I have purple, green, or some other pwm pattern, current drops dramatically. I'm pretty sure they state maximum rated current that led will pull.

Try looking super closely at your leds and see if you can spot individual colors. They will look slightly offset when they light up.


Does the PDF of the LED model not have that info? Its linked in the first post.
 

UltraTaco

Member
Joined
Oct 28, 2017
They're based on 5050 chip. It's the same chip as my light strip, but diode is off by 1 number. Mine is 2811b. Its powered by 12v rail. I'm using roughly 1.5amps for 150 leds in white. Sorry more math for you, I'm away from home.

Your math looks pretty close. Right where it should be:shrug: sorry I cnt hlp you any more. You could connect all leds to separate power source as a test and check current draw. That will give you most definite answer.:thup:
 
OP
Helgaiden

Helgaiden

Member
Joined
Jul 14, 2003
They're based on 5050 chip. It's the same chip as my light strip, but diode is off by 1 number. Mine is 2811b. Its powered by 12v rail. I'm using roughly 1.5amps for 150 leds in white. Sorry more math for you, I'm away from home.

Your math looks pretty close. Right where it should be:shrug: sorry I cnt hlp you any more. You could connect all leds to separate power source as a test and check current draw. That will give you most definite answer.:thup:

Hey if you're drawing only 1.5A for 150 LEDs and they are similar model to these, then i feel pretty safe with less LEDs to also do white. Thank you for your help!
 

UltraTaco

Member
Joined
Oct 28, 2017
Mine are 12v though..but still, you will likely be safe with room to spare.
Another quick and dirty way to check if you're overloading too much or not is to plug one by one to see how much dimming you get with additional load.
 
OP
Helgaiden

Helgaiden

Member
Joined
Jul 14, 2003
Mine are 12v though..but still, you will likely be safe with room to spare.
Another quick and dirty way to check if you're overloading too much or not is to plug one by one to see how much dimming you get with additional load.

Yeah i cant do that yet, still need certain parts before i can turn it on. Otherwise i would.