Corsair H50 - How to Connect New Push/Pull Fans

Hello,

I just picked up a pair of Scythe S-Flex F 120mm fans to run as exhaust over my corsair h50 radiator. However, I had a question about how to hook up the fans wires:

Currently I have the stock h50 fan pulling and the stock cooler master case exhaust fan (case is HAF922) pushing. The CM fan is hooked up to a 3pin header and the Corsair fan is hooked up to 4pin.

The new fans have 3pin connectors but include 4pin and molex adapters.

From what i read:
3pin headers = fail safe feature + power
4pin headers = fail safe feature + power + auto controlled fan speed?

In any case the fans only have 3 wires coming off the motor so I figure if I adapt one to my 4pin header thats open and one to my 3pin header then they will both run at the same RPM?

Essentially I just don't want them to run at mismatched RPMS if one is auto controlled and one is not. But i feel like if it doesn't natively have a 4pin connection then it cant operate with auto control.

Any help greatly appreciated.

black wire is ground
red wire is +12v
yellow wire is RPM
blue wire is a PWM signal (@ 5v)

the pwm signal goes to a circuit in the fan that essentially turns the fan on and off really really quickly (time on vs time off is called duty cycle). If the fans are being controlled by voltage regulation (bringing the voltage on the +12v line down) then they will run at the same speed. If not, they will run at mismatched rpm's if they are not the same RPM of fan. Matching rpm's through a single header is impossible without a circuit going to one fan. If you just connect both sflexes to the same header and put them both on the h50 you'll have nothing to worry about though.

I see;

How would I go about connecting them to the same header? I've never done that before, sorry

You can plug a 3-pin fan plug into a 4-pin fan header on the mobo. It is keyed so that it will only fit 1 way. You may loose fan speed control, though; depends on the capabilities of the mobo.

But if you turn off fan control for both fan headers then both fans should run at 100%.

There are 2-to-1 adapters if you want to plug both into the same fan header or you can wire it up yourself if you're handy.

jason4207 said:

You can plug a 3-pin fan plug into a 4-pin fan header on the mobo. It is keyed so that it will only fit 1 way. You may loose fan speed control, though; depends on the capabilities of the mobo.

But if you turn off fan control for both fan headers then both fans should run at 100%.

There are 2-to-1 adapters if you want to plug both into the same fan header or you can wire it up yourself if you're handy.

Click to expand...

Ah I see. Where would I turn off fan control in the BIOS I imagine?
I really just want both to run at 100% all the time.

yep, just turn it off in the bios and connect the fans to the mobo...alternatively you can connect them directly to the PSU