Question case fan to cpu fan header.

Jun 15, 2018
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let's begin from the beginning

I'm planning to buy a new cooler, one of those metal block thing m'jiggy's, that fits 120mm fans on it. This means that I'm swapping out my stock cooler for two 120mm fans. My plans are to fit it with the Cooler Master MasterFan MF120ARGB. BUT!!! I've heard that the normal case fan runs on around 12V, and the cpu fan on 24V. So, I'm affraid that i'll completely fry the RGB-illuminated fans (which are €40,- for a 3-pack, VERY expensive) by plugging them into the cpu_fan slot.

So do those fans fry their insides if plugged in?
if yes, do i need to change my computersettings in the BIOS or AI Suite 3 so that the fans get their 12V, or does the computer do this by itself?
if no, does this not matter, an can I plug in these fans just like your standard 4-pin gpu cooler, without anything happening?
 
No, the CPU fans run on PWM or 12V (it may or may not work on voltage, so you mayjust get stuck with a constant fan speed.) PWM fans are recommended for the CPU, but you could use 12V fans if you had to. Just buy a PWM fan to use for the CPU.
 
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What you "heard" is wrong. Virtually all computer case fans and CPU cooler fans (INCLUDING your Cooler Master MasterFan MF120R ARGB units) use a 12 VDC supply, and so that is ALWAYS what the CPU_fan header puts out. In your case, the fan is of the newer PWM design to it will be just fine connected that way.

Your confusion MAY be linked to a different thing entirely. Those fans contain RGB lighting units built into their frames, and RGB coloured LIGHTS (not the motors) do come these days in two different and incompatible types. There are plain RGB types that use a 4-pin connector and a 12 VDC power supply line, and then the more advanced Addressable RGB (aka ADDR RGB or ARGB) type that uses a 3-pin connector (like the 4-pin but missing one pin) and a 5 VDC power line. Such a fan comes with TWO separate cables - one for the fan motor ending in a standard female (with holes) 4-pin fan connector, and the second with a wider female 3-pin (4-1 holes) ARGB connector. Cooler Master sells separately (included of you buy a 3-pack) a simple box for manual control of the LIGHTING parts of these fans. But IF your mobo has a 3-pin ARGB header on it (not just the 4-pin plain RGB type), you can connect the lighting cables from your fans to that header and use the software utility supplied free by your mobo maker to power and control the lighting effects by software, rather than by a hard-wired manual box. To do that you probably need an RGB Splitter to connect two or three such fans' lighting cables to a single mobo ARGB header, and Cooler Master sells those, too.
 
Jun 15, 2018
26
0
30
0
What you "heard" is wrong. Virtually all computer case fans and CPU cooler fans (INCLUDING your Cooler Master MasterFan MF120R ARGB units) use a 12 VDC supply, and so that is ALWAYS what the CPU_fan header puts out. In your case, the fan is of the newer PWM design to it will be just fine connected that way.

Your confusion MAY be linked to a different thing entirely. Those fans contain RGB lighting units built into their frames, and RGB coloured LIGHTS (not the motors) do come these days in two different and incompatible types. There are plain RGB types that use a 4-pin connector and a 12 VDC power supply line, and then the more advanced Addressable RGB (aka ADDR RGB or ARGB) type that uses a 3-pin connector (like the 4-pin but missing one pin) and a 5 VDC power line. Such a fan comes with TWO separate cables - one for the fan motor ending in a standard female (with holes) 4-pin fan connector, and the second with a wider female 3-pin (4-1 holes) ARGB connector. Cooler Master sells separately (included of you buy a 3-pack) a simple box for manual control of the LIGHTING parts of these fans. But IF your mobo has a 3-pin ARGB header on it (not just the 4-pin plain RGB type), you can connect the lighting cables from your fans to that header and use the software utility supplied free by your mobo maker to power and control the lighting effects by software, rather than by a hard-wired manual box. To do that you probably need an RGB Splitter to connect two or three such fans' lighting cables to a single mobo ARGB header, and Cooler Master sells those, too.
thanks, now it's clear.

I wasn't sure if they ran on the same voltage because the cpu fan runs faster. And my tought was: "the faster the fan, the more power it uses"
 
Your last thought is correct. WE actually misinform ourselves a little on these things. We say it is a 12 Volt fan. But the truth is, we mean it is designed to run on a MAXIMUM of 12 VDC to reach max speed and air flow, but it can run slower if we reduce the voltage fed to it. Or, in the new PWM control system, the supply voltage is always 12 VDC, but the motor uses a little chip in its case and the extra PWM control signal from the mobo to modify the electrical supply and reduce speed.
 
Your last thought is correct. WE actually misinform ourselves a little on these things. We say it is a 12 Volt fan. But the truth is, we mean it is designed to run on a MAXIMUM of 12 VDC to reach max speed and air flow, but it can run slower if we reduce the voltage fed to it. Or, in the new PWM control system, the supply voltage is always 12 VDC, but the motor uses a little chip in its case and the extra PWM control signal from the mobo to modify the electrical supply and reduce speed.
Largely correct with some finer points. Maximum voltage ensures maximum power to fan's motor, with lower voltage motor produces less power and air resistance slows it down so changing voltage may not produce consistent speed reduction depending on circumstances
PWM (Pulse Width Modulation) is kinda self explanatory, controller sends 12v or reduced voltage pulses of various length and frequency and so regulates fan speed. RPM sensor built into fan motor provides feedback to controller in either case.
Just to mention the motor in such fans and pumps, it's a brushless, permanent magnet, poli-phase motor in which an electronic oscillator changes DC current into poli-phase current providing circular charging of separate coils in the stator and circular magnetic field while permanent magnet is built into rotor holding fins.
 
I'll disagree with the technical details of your second paragraph, CountMike.

The PWM control system in computer fans that use that name is NOT the same as the way PWM power sources are used to control DC motors in larger industrial applications. (No, you did not say it was - I'm just pointing out to others that it is different.) In the brushless computer PWM fan, the fan receives 12 VDC from Pin #2 at all times. The circuitry in the motor case that does the brushless switching to simulate the effect of a brush-and-commutator system in standard DC motors also has an added chip that applies the PWM signal supplied from Pin #4 to that 12 VDC power source before it flows through the motor's windings, and at that point the power supplied does look very much like a common Pulse Width Modulated DC supply to industrial DC motors. By the way, the PWM signal operates at 20 to 25 KHz usually in these computer systems. But the resulting voltage fed to the motor windings actually stays at 12 VDC peak, switching from 12 V to 0 V over and over as the PWM signal directs. The result, of course, is that the current flow through the windings also switches from max to none, etc., producing torque pulses. But since the torque is not at max all the time, and the motor is experiencing resistance to torque (it is driving fan blades to move air) it does not turn at the motor's rated max speed unless the PWM signal actually calls for 100% On (i.e., full speed).

Doing things this way instead of the way older larger PWM power supplies do it has a few advantages. It means the mobo circuits for the fan headers do not have to have DC Amplifier outputs that can supply PWM-pulsed power at 12 VDC max and up to 1.0 A at 100% On state - they can be simpler and very similar to what already was on mobos for the older Voltage Control Mode. The circuit elements inside the motor that do the commutator simulation job required by small brushless fans can still receive a smooth reliable DC supply from Pin #2. (Note that makers of these fans specifically tell you NOT to try to feed such motors with PWM power that is already modulated into a pulsing source, as older methods do for large DC motors.) And, it made it much easier to build backward compatibility features into the new 4-pin PWM fan designs so that mobo makers and users have a relatively easy way to adjust to either fan type.

Regarding the speed signal sent by a fan back to its host mobo header, as far as I can tell the mobo speed control system does NOT use that at all - it is NOT a speed feedback control system. The control loop actually is a TEMPERATURE controller that uses Temperature measured at a relevant sensor as the feedback information. The control loop simply sends out signals to manipulate the fan speed to achieve its temperature target and actually does not care what the speed is. (In fact, if you have a "2-pin fan" - that is, a fan designed to connect to a PSU source only with no control and no speed signal output from the fan - that fan CAN be connected to a mobo header using the older Voltage Control Mode and its speed can be controlled perfectly by that header without any speed signal.) BUT, users are interested, and that signal is already available inside the brushless motor - it is generated for use in the brushless switching circuits to synchronize the switching action with rotor position - so it's easy to access and display. PLUS, there is a more practical use of the speed signal, too. That is FAILURE detection, the secondary function of each fan header.
 
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