Worried I might be overloading my fan headers

[Cyber Akuma]

I have a system that has three proprietary fans on three headers, they are all 12V and 0.95A and look like this:



I am going to be replacing them with standard fans using an adapter so I can put more fans on the system, I will be replacing them with these:

https://www.amazon.com/gp/product/B097C717Y4/

Which according to the specs have a max draw of 0.15A (How are they that much less?)

But I will need to daisy-chain more fans to that header, one of them is no big deal as I will just be adding another single 80mm fan, but the other I will be adding several and I am worried it might be too much.

I will also be adding another 120mm fan, most likely this one which says it has a max draw of 0.05 Amps (How is it that low for a bigger fan?):

https://www.amazon.com/gp/product/B00650P2ZC/

And possibly these two 60mm fans which each pull 0.08 Amps:

https://www.amazon.com/dp/B00VXTANZ4/

Altogether this should be well under what the single fan originally pulled, 0.95A vs 0.35A (at least if I am to believe it's specs), but I am going to be basically daisy-chaining four fans to a single header which worries me if that will be safe, especially since it will be four fans of three different sizes and power draw. Is it safe to do this?

 

[Tsumi]

Is that Foxconn a 5000+ RPM fan? If not, there's no way it's actually pulling 0.95 amps continuously. The 0.95 rating might just be the instantaneous startup current rating rather than the actual continuous rating, which is what is being used as the rating for all of the other fans.

The Noctuas are probably using a more efficient motor and bearings that have less friction than the Arctic fans. Also, keep in mind that air resistance (and thus power needed to overcome it) goes up with the square of airspeed.

You also are not daisy-chaining fans (you will get some pretty crappy results if you actually did). You're running them in parallel and the board doesn't care what is connected in parallel as long as it doesn't exceed the power delivery capabilities. Most boards will shut down the header if limits are exceeded.

 

[Cyber Akuma]

You also are not daisy-chaining fans (you will get some pretty crappy results if you actually did). You're running them in parallel and the board doesn't care what is connected in parallel as long as it doesn't exceed the power delivery capabilities. Most boards will shut down the header if limits are exceeded.

I kind of am. The Arctic fans include a plug to connect a second fan to them, and I only have dual fan splitters. Basically I will plug the Arctic 92mm fan into the header, and then a splitter into that 92mm fan, one will go to the 120mm, and the other will go to another splitter for both 60mm fans.

If that's a bad idea I could just get a three way splitter so the 120 and two 60 plug into the daisy-chain cable of the 92.

 

[Tsumi]

I kind of am. The Arctic fans include a plug to connect a second fan to them, and I only have dual fan splitters. Basically I will plug the Arctic 92mm fan into the header, and then a splitter into that 92mm fan, one will go to the 120mm, and the other will go to another splitter for both 60mm fans.

If that's a bad idea I could just get a three way splitter so the 120 and two 60 plug into the daisy-chain cable of the 92.

That's like daisy chaining power strips. While the power strips are physically in a daisy chain, everything is still technically in parallel. The danger with daisy chaining splitters is the possibility that multiple connections will generate too much resistance and thus heat, potentially melting the connection. Basically what happens is the voltage will drop after each connection, causing whatever is connected to increase the amperage drawn to maintain the same power level if it needs to maintain the same wattage. I doubt that the low amperages you're working with will be of any issue and fans will simply work at reduced speed/power with voltage drops rather than increase amperage to compensate.

 

[Cyber Akuma]

So should I get a three-way fan splitter to plug into the 92mm fan instead of daisy-chaining splitters off the built-in splitter in the 92mm fan? Or is the difference going to be so small that it's better not to spend that extra money?

 

[Tsumi]

The difference is so small I don't see any issues.

 

[xDiVolatilX]

My case has 5 fan wires, I split each one into 3 for 15 fans. All 15 are populated. Never had a single problem lol. Although it's not off the mb header it is a sata fan hub on the case built in. Still 5 to 15 is pretty good lol.

 

[doyll]

Keep in mind all fans draw 4-6 times more than rated power when starting up!!

Ever notice everyone talking about loosing a fan header noticed it after starting system? It's because startup load is so much higher than running, so that's when header is overloaded and dies.

What Tsumi said about connectors is very true, but motor startup load increase is much greater than connector impedance load increase.

Quick rule of thumb for me is multiply typical running load rating of fan by 4. Keep total load per header at 1amp or less. Haven't lost a fan header yet, and my first PCs were IBM Personal Computer and Amiga. That was dial-up phone modem times.