Jan 21, 2021
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I finished building my first pc and I didn't have enough fan ports on the motherboard so I ordered a fan hub but when I connected all my fans to the hub and connected it all together but the fans were pulsing and I checked what setting were on my fans using the RGB fusion software they were on the default setting. When I put put my hand on the motor i could feel the fans turning off and on.
 

Paperdoc

Glorious
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alceryes is absolutely correct. See your mobo manual p. 22. To get into BIOS Setup, boot your machine and immediately hold down the "Del" key. Don't just tap it - hold down until the opening screen of BIOS Setup appears (p.23). At bottom right click on Smart Fan to get to the screens to configure each fan header. See p. 26 for details, but no further photos.

You have all your case fans connected to one fan Hub, right? So that Hub is plugged into one of your mobo SYS_FAN headers. You need to know which one. In BIOS setup you need to choose THAT specific SYS_FAN header to configure. Set this way
Fan Speed Control to Manual - this will allow customization (below)
Fan Control Use Temperature Input set to Motherboard, not CPU
Fan Control Mode to PWM
Fan Stop to Disabled so they never actually stop
Temperature Warning Control to 70 C, but you may need to change that later if you get too many warnings of high temp on your mobo
Fan Fail Warning to Enabled so it will warn you if a case fan fails. BUT this failure monitoring system cannot monitor ALL your case fans, so you should check from time to time that they all are still working.

When you set the Speed Control to Manual, you should be able to see a screen of a table or graph of what speed the fan should run for different measured temperatures. This is what you need to adjust. Apparently your system tends to operate right around one of the places where there's a need to change. So you need to move the spot for that temperature setting point either higher or lower, so you get away from frequent changes. If you set it higher, don't make it very high - that would delay an increase in cooling. You can move it to a lower temp, and then your fans will operate most of the time at the higher speed step they have been using, and will slightly over-cool your system.

When you are done, use Esc back to Main Menu, then F10 to reach the Exit Menu (p.38). Choose Save & Exit Setup to save your new settings and reboot.
 

alceryes

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Are they ALWAYS pulsing regardless of your temps? What happens if you run a benchmark (like RealBench) to heat up the components? What happens if you just let it sit at a blank desktop? Remember to monitor your CPU temps - don't let them get above 95C when testing/benchmarking.
Also check your fan thresholds. If you have thresholds right around the normal operating temperature of your CPU (assuming your case fan thresholds are using your CPU temp), then they will regularly speed up and slow down.
 
Jan 21, 2021
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when i first turn the pc on the fans are working fine but when i start playing the fans start pulsing as my pc heats up . do you know any software so i could controll my fan speed (i have a aorus b450 elite motherboard). How do you check the fan thresholds.

Edit:
my fans came with my case and i used this fan hub
i first plugged in four fans into the hub but it started flashing so i took out one and it solved the problem but later on it started flashing again as my pc heated up.
 
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alceryes

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Okay. So, if the pulsing is what I think it is, it's totally normal. You are hitting a temp threshold. I'm assuming that its mainly your CPU fan that you hear pulsing. To verify, grab the inner tube from a paper towel roll, put one end against your ear, and move the other end around to all the fans in question to see which one(s) it is. First thing to find out is which fans are 'pulsing'.

When you hit a temp threshold, your fan(s) speed up to the next RPM level, as dictated by the fan curve you set. However, when your fan(s) speed up, they cool your CPU down below the temp threshold so your fan(s) then spin down. I believe some motherboards have a delay once a threshold has been tripped to prevent this spin up and spin down behavior but when you are experiencing is very common. To fix this, you could raise that threshold so that it doesn't get tripped until your CPU really heats up. This requires monitoring of your CPU temp to make sure it's not getting too hot. So, in the fusion software adjust the fan curve a bit higher. If it's your CPU fan that's making the noise you'll need to adjust that curve as well. If you have it on CPU FAN motherboard header you may be able to change the curve in BIOS.
 
Jan 21, 2021
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The software that i have can only controll the led colours it cant controll fans speed or anything else. the fans that are pulsing are two front panel fans and two fans that are at the top the cpu fan is ok
 

Paperdoc

Glorious
Ambassador
alceryes is absolutely correct. See your mobo manual p. 22. To get into BIOS Setup, boot your machine and immediately hold down the "Del" key. Don't just tap it - hold down until the opening screen of BIOS Setup appears (p.23). At bottom right click on Smart Fan to get to the screens to configure each fan header. See p. 26 for details, but no further photos.

You have all your case fans connected to one fan Hub, right? So that Hub is plugged into one of your mobo SYS_FAN headers. You need to know which one. In BIOS setup you need to choose THAT specific SYS_FAN header to configure. Set this way
Fan Speed Control to Manual - this will allow customization (below)
Fan Control Use Temperature Input set to Motherboard, not CPU
Fan Control Mode to PWM
Fan Stop to Disabled so they never actually stop
Temperature Warning Control to 70 C, but you may need to change that later if you get too many warnings of high temp on your mobo
Fan Fail Warning to Enabled so it will warn you if a case fan fails. BUT this failure monitoring system cannot monitor ALL your case fans, so you should check from time to time that they all are still working.

When you set the Speed Control to Manual, you should be able to see a screen of a table or graph of what speed the fan should run for different measured temperatures. This is what you need to adjust. Apparently your system tends to operate right around one of the places where there's a need to change. So you need to move the spot for that temperature setting point either higher or lower, so you get away from frequent changes. If you set it higher, don't make it very high - that would delay an increase in cooling. You can move it to a lower temp, and then your fans will operate most of the time at the higher speed step they have been using, and will slightly over-cool your system.

When you are done, use Esc back to Main Menu, then F10 to reach the Exit Menu (p.38). Choose Save & Exit Setup to save your new settings and reboot.
 
Jan 21, 2021
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i have done all the things you have told me but when you said "Fan Control Use Temperature Input set to Motherboard, not CPU " the options that were there were System 1, Chipset, CPU, PCIEX16, VRM MOS, VSOC MOS
 

Paperdoc

Glorious
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You have me confused, and maybe you are confused yourself. Your first post speaks of "pulsing" fans, and says you can verify that by feeling them "pulsing" as they run. But you also said you have configured them using the RGB Fusion software. Then your last post says that, although you have done as advised, they still are "flashing". I THOUGHT your first post was about fan SPEEDS changing, but now you are using "flashing" which sounds line LIGHTS changing. Which is your problem? Or, are BOTH things happening?
 

Paperdoc

Glorious
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Now I'm getting it, and I can see two parts of the problem. That device you have, which is said to be a Fan Hub, is NOT. It is a different device called a SPLITTER. A Splitter merely connects all its fans in parallel to the host header on the mobo, and hence ALL of the fan electrical power must come from the mobo header. All such headers have a limit on power available, typically 1.0 A max. Most current simple fans draw from 0.10 to 0.25 A max each, and you have SIX fans. So that alone says it is entirely possible that your system is trying to use too much power from a single fan header. A real fan HUB does it differently and works only with 4-pin fans. What it really different about a HUB, though, is that it has an extra "arm" that must plug into a SATA or Molex power output connector from the PSU to give the Hub (and all its fans) more power than any header can do. You do NOT have one of those.

Next is a subtle detail of the fans. I see the case says it includes "6 Halo Single-Ring Blue LED Fans". It does NOT say RGB Fans, or some such. I expect each fan has ONE cable from it that plugs into a fan header, and NO other cable. That is called a LED Fan, an earlier version of lighted fans. In it, the LED's added to the frame are normally all ONE colour and are simply connected in parallel with the motor for electrical power. This increases the power requirement of each fan to the range of 0.35 to 0.50 A each. It also means that there is NO way to connect the fan lights to a mobo RGB or ARGB lighting header for power and control of them separate from the motor. Thus no utility like RGB Fusion can do anything for the lights.

So, those six fans connected that way are overloading the mobo fan header you have used, and its power output to the fans fails. When that happens, BOTH the fan speed AND the light brightness fail. That is what you are seeing.

So, what to do? You need a different way to connect six fans. Further, which way depends on the fan motor type. Does the cable from each fan end in a connector with THREE holes, or FOUR? The answer tells us how the fan speeds can be controlled, and hence what device to use. Next, tell us the maker and exact model number of your mobo. We need to look up its detailed specs for how many fan headers of which type you have to use, because it is VERY likely you will need to use more than one for those six fans.

Lastly, IF you can find a label on a fan hub, tell us what it says about electrical power. I'm sure it will say 12 VDC. But then what does it say about Amps or Watts?
 
Jan 21, 2021
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i have three fans connected to the fan splitter the other three are connected to the motherboard. All the fan plugs are three pin headers
it says 12vdc but i cant find amps or watts
 

Paperdoc

Glorious
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OK, so you have six fans. Of these, three are plugged into mobo headers, and three are on the Splitter connected to a fourth header. I said your symptoms tell me that arrangement of three fans is too much power draw from one header. Your said when 4 fans are on the Splitter it cannot work. With three fans is can start, but stops working when you do any real work and the system heats up and the fan speed up. With two fans on the Splitter it works OK. All this confirms: the fan loads are big enough that THREE fans is too heavy a load for one mobo header. So you need to re-arrange to having only TWO fans per header.

I suggest you buy two more Splitters. They may be just like you have. Or they may be very simple two-output Splitters that look like groups of cable arms, like this

https://www.amazon.com/Splitter-Extension-Converter-Matherboard-Computer/dp/B08PFCGJFD/ref=sr_1_9?dchild=1&keywords=fan+splitter&qid=1613275957&sr=8-9

Each only needs two outputs, because that's all you can connect to one header. Use three Splitters to connect two fans each to three headers, leaving you with one header unused. Most Splitters you buy have four-pin outputs, and are just fine to use with 3-pin fans.
 

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