Help with making cooling fan setup quieter w/ pwm hub

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Averytw

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May 13, 2015
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Hi guys,

Up until now, I've just ran my case fans off Molex connectors, however that's a bit noisy. I'd like to switch to something a bit quieter that can adjust based on temperature. So, I'd like to get rid of the stock fans, and switch to quieter PWM fans.



Soooo, hopefully some quick questions:

- For a PWM hub (Maybe Silverstone CPF04), do all of the fans need to be the same for accurate RPM readings? ie Can I hook up a 120mm and 140mm fan to the same hub?



- Should I have all PWM case fans using the 4-pin chassis header, or should I split them up and have some on the CPU header? (Is that even possible?) I'm not sure why I'd do this, but I thought I'd ask?



- Are (2) 120mm fans to push, and (1) 140mm fan at the top to pull enough for airflow? (besides the cpu & psu fans)



- My cpu fan requires one header to always be on for the radiator, and one to be temp based for the fan. Currently, I have the radiator pump hooked to a chassis fan slot. Is there a better option for an always-on component like that? The power header maybe?



Relevant system info:

- Rosewill Challenger Case w/ (1) Front 120mm fan, (1) top 140mm fan, (1) side 120mm fan. Optional: (1) side 120mm fan, (1) rear 120mm fan.

- Asrock Z77 Extreme4 motherboard w/ (1) CPU 3-pin, (1) Cpu 4-pin, (2) Chassis 3-pin, (1) Chassis 4-pin, (1) Power-fan

- Corsair Hydo series with with fan for radiator, one power connector for radiator (ie requires 2 fan headers)



On behalf of my roommate that is tired of hearing a hairdryer, thank you SO much for taking the time to read and answer! :)
 
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If you use a PWM hub and fans of different sizes, all fans will share the same control signals. These signals do not control either voltage or amps directly. I won't go into details of PWM control for now, but the result will be that all of them will change their speeds according to those controls, and thus their air flow rates. Probably there won't be exact matching of air flows, but that's not a big problem. As I said, there are other factors also affecting air flow rates, anyway.

With the H60 cooler system, the manufacturer says the radiator 4-pin fan should be connected to the mobo's 4-pin CPU_FAN port for automatic control of CPU cooling. The system's 3-pin connector to the pump unit should go to the PWR_FAN or to a CHA_FAN port...
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Averytw

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@Timeconsumer I'm currently running the stock fans but I'll be upgrading. Part of the problem is stock and the other part is no ability to idle due to molex/3pin which is why I'm asking about pwm hubs.

@Mcnumpty yeah that's similar to the silverstone cpf04 i mentioned. Can you run multiple sized fans off one hub like that?
 
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Paperdoc

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Re your questions in order:

1. You CAN use a PWM fan hub like that Silverstone unit, but ALL of the fans you connect to it MUST be 4-pin ones. It does not matter which size they are. Re: "accurate RPM readings", only ONE of the fans connected will have its speed displayed. NONE of the others will. The hub cannot forward to the mobo any more than one fan speed. The one that IS sent to the mobo for display is the one connected to a corner port that is marked off separately.

2. Since the fans in question are all case ventilation fans, the hub definitely should be connected to the only 4-pin mobo Case Fan port. You MUST connect it to a 4-pin port, and this one is the only one that is automatically controlled by a temperature sensor in the MOBO, and not by the internal CPU temperature. It is the temperature of certain mobo components, not of the CPU, that should guide case ventilation.

3. To estimate air flow, fan diameter is not the best guide. Look for air flow specs (CFM) of the fans you propose to buy. Even then, some things you cannot calculate. For example, your intake fans really should have dust filters in front of them (which you need to check and clean regularly). These filters, however, reduce air flow through the fan by an unknown amount. And of course, once the automatic control is running and slowing the fans down to meet temperature targets, you have no way of knowing what the actual air flow is.

4. To answer your last question requires a specific cooler model number. Corasir makes many with different connections. For example, one I looked at in detail (the model H100i) uses one Y cable for power. One connector on it goes to a SATA power output connector from the PSU for power, and its other connector is a common 3-pin fan connector that really only sends the pump's speed signal to the mobo, so it MUST be connected to the mobo CPU_FAN connector. The actual radiator fans plug into special ports on the pump unit itself for their power. Your description, however, says you plug separate connectors for pump power and radiator fan power into different mobo ports. So we need to know exact model number.

HOWEVER, I will say that, if your radiator fan(s) require connection to a constant 12VDC power supply, you have three choices. One is any unused mobo Chassis Fan port, BUT then you really need to go into the fan speed control system for that port and set it manually to run full speed always. You do NOT want to have the mobo's automatic temp control system reduce the voltage supplied to these fans. The second would be to use the mobo PWR_FAN port. This port is designed for use solely as a speed signal input from a set of special fan-like leads from the PSU, but not all PSU's have these. So if you are NOT using this mobo port as intended, you can connect any 3-pin or 4-pin fan to it. Many mobo makers have fitted this port with Ground and +12VDC supplies on Pins 1 and 2, so a fan connected here will always receive the full 12 VDC, which is just what you need for the radiator fan(s). The third option is to connect those fans directly to a PSU power output connector (4-pin Molex for an IDE device, or a SATA power connector) via an appropriate adapter.

Let us know the model number of your Corsair cooler system for more specific advice on its power connections.
 
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Averytw

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@Paperdoc Thanks for the response!

For the pwm hub, if i have the rpms based on a 120mm fan but also have a 140mm fan, won't the 140mm get the same amps as the 120mm and not be as fully utilized?

I have the H60 corsair cooler. It has a 3pin for the radiator and a 4pin for the fan. I'm guessing i should upgrade that fan along with the case fans?

Thank you for the tip on the dust filters!
 
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Paperdoc

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If you use a PWM hub and fans of different sizes, all fans will share the same control signals. These signals do not control either voltage or amps directly. I won't go into details of PWM control for now, but the result will be that all of them will change their speeds according to those controls, and thus their air flow rates. Probably there won't be exact matching of air flows, but that's not a big problem. As I said, there are other factors also affecting air flow rates, anyway.

With the H60 cooler system, the manufacturer says the radiator 4-pin fan should be connected to the mobo's 4-pin CPU_FAN port for automatic control of CPU cooling. The system's 3-pin connector to the pump unit should go to the PWR_FAN or to a CHA_FAN port of the mobo. I presume that means this unit needs a full and constant 12 VDC supply for the pump. So IF you use a CHA_FAN port, I recommend you set it to operate NOT under automatic control, but manually set to full speed always.

I don't see any need to change that 4-pin radiator fan. It is probably the more significant noise generator in your CPU cooler system, and it already is under mobo automatic control to reduce its speed whenever possible. Just keep it plugged into the mobo's CPU_FAN header.
 
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mcnumpty23

mcnumpty23

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yes you can though all fans will run at roughly the same speed --not an issue for me as i have plenty radiator area so having them all run very slowly works for me as its silence i want-- i just set a custom fan curve and as my pumps are 4 pin pwm i can also run those off it

 
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