Sorry for not getting back sooner...haven't been feeling well.
Based on the information at hand, and without being able to test it at home with my lab equipment, I can't tell you how to safely proceed with a 100%
guaranty you wouldn't damage anything.
Without knowing more, my concern is that you could damage (or already have damaged) fan circuitry or the LEDs by simply applying voltages at random.
For maximum protection of the fan circuitry, my recommendation based on what I've been able to find is either get more info directly from CoolerMaster or find someone with that exact configuration of that model fan who can advise you.
I can only provide possibilities, not absolutes.
But, I'll give you what I've found.
Comparing your description of the wiring to what I've seen, things are even more confusing. ALL the specs I could locate on that fan say it is a "3-pin connector
" fan, not 4-wire
, and not even 3-wire
. Although there is a suggestion from ONE reviewer that his fan had independent control of the LEDs...which suggests there may be more than one version of that model out there, and hence one version could be a 4-wire fan, OR you could have a fan that has been modified by someone in an attempt to provide independent control of the LEDs
. But, I didn't find any explicit reference to a 4-wire version of that model.
Although they do provide a "standard" Berg 3-pin to Molex 4-pin adapter to get +12V and Ground from a standard 4-pin IDE disk drive power connector, and I'm pretty sure that's not what you're talking about. And since they do provide that adapter, that strongly suggests to me the LEDs are hard-wired to the +12V fan-motor power connector in that version of the model.
I point out the 3-pin berg to 4-pin molex adapter that comes with the 3-pin connector version of this fan ONLY brings out the ground and +12V connections from the 3-pin connector. The 3rd wire (IF it exists) is ignored.
The info I've gathered SUGGEST that the Red and Black wired connector is the fan motor power connector. That would SUGGEST that the Black and Yellow pair are the LED power wires. But that is by no means a sure thing, and it assumes this is NOT a user-modified fan.
With the exception of that ONE review, all reviewers in multiple locations I checked-out corroborated no ability to independently control the LEDs. That strongly suggests to me that in their 3-pin connector fan configuration, the LEDs are hard-wired into the +12V fan-motor power input line.
There is no explicit reference to that fan providing an RPM sense wire, regardless of the spec saying it has a 3-pin connector
. However, manufacturer's often use 3-pin connector to denote an assumed RPM feedback capability. But unfortunately not all manufacturer's are consistent and I know
that many case fans are listed as 3-pin connector
but only provide 2 wires going to the connector...which of course means there is no standard RPM feedback connection. This is usually the situation with cheap case fans. The 3-pin connector
is only to provide compatibility with the standard mobo 3-pin berg header, and it maintains voltage polarization of the connector to protect the fan circuitry. And, since I've seen this fan selling for $12, I'd have to put it in the "cheap" category...especially since it also uses a sleeve-bearing...the cheapest and most unreliable bearing possible.
There were suggestions this CoolerMaster fan is designed to run at a flat 700rpm 100% of the time especially considering it's a 19dB fan...extremely quiet even running full-out. Further, IF the LEDs are hard-wired into the fan motor's +12V line, then the manufacturer's generally
seem to assume the fan will be running from a straight +12v feed, and not PWM speed controlled. However, that does NOT prevent a user from doing so, it's just not a typical mode of operation. If an RPM sense wire is provided, it might be used primarily to provide a fan-failure sense capability. There are even 3-pin to 4-pin molex connector that split out the RPM sense wire to a separate 3-pin connector
to provide exactly that capability. The fan ALWAYS runs at full speed, but the RPM sensor provides ability to alarm if the fan stops rotating or for some reason starts to slow-down (e.g. bearing failure). See
(note: viewing this may adjust the window size of your browser!)
But, as I said above, the adapter provided with the 3-pin connector version of this fan does not do that.
Specs show the fan has 2 DC current requirements. Unfortunately it again doesn't absolutely clear things up. That could suggest either the fan running at PWM controlled minimum and maximum speeds, OR it could indicate the fan running with and without the LEDs turned on, or a combination of both.
Both black wires are going almost certainly to be Ground. The fan motor-control circuit itself can take up to +12VDC so there is little danger of damaging the fan motor-control circuit by applying ground and then applying +12V to the red or the yellow wire to see what happens. But, the danger in doing so is you could damage the RPM feedback circuit (if it exists). Or the LEDs could be damaged IF they need an external current-limiting resistor (however that is somewhat unlikely).
Regardless, and I advise against this
, IF you plan to go ahead and do more testing to determine if you have wires for separate LED power, then I would recommend using a 1000 ohm 1/2 Watt resistor in series with your power supply. I also suggest you limit the supply voltage to 6 volts. Any connections you make should be extremely
brief, but should still dimly light the LEDs for that fraction of a second. And by "extremely brief" I mean like 1/10 of second or less. If you don't see LEDs light-up, then they are possibly already destroyed, or there is an internal break in the wiring of the LEDs, or there is no separate power input wire for the LEDs. (Note: with the resistor and reduced voltage, it is highly unlikely the fan blades will "tick" (move slightly) when you apply power to either the red or yellow wire)
edit to add:
comment about sleeve-bearing
moved a paragraph