My 3pin fans change speed?

Lunawolfy · 1 Jul 2011 at 09:04

I currently have an H60 with 2 Gentle Typhoon fans @1800rpm in a push/pull config on my rad.

They are 3 pin fans attached to my CHA FAN 1/2 respectivly (pump is on CPU header)

What bewilders me is that they are 3 pin fans with no support for PWM, yet they currently sit at 1100 RPM, if I chuck IBT at the CPU, within a few seconds on the temp rising they hit around 1650 RPM.

Whats going on here? I've tried playing with the BIOS but I can't find any good setting, they don't seem to do anything (I'd like to raise idle ran a couple hundred RPM)

PhillyDee · 1 Jul 2011 at 09:09

They are changing through voltage control. This was used before PWM and is usually used on the rest of the fans. Either connect to a molex with an adapter, or chase through the BIOS and turn voltage control off on those headers/

IPAddis · 1 Jul 2011 at 18:48

Or just leave the fans on auto and change the fan profile (on the Asus board, I have 3 chassis fans running on the Standard Profile).

ETA if the H60 pump runs off the fan headers, then I would second turning off the fan control.

setter · 1 Jul 2011 at 18:57

The H60's pump will be fine on the cpu fan header. Asus removed speed control for 3 pin fans on their cpu fan headers a few years ago. Their boards can only control 4 pin PWM fans on the cpu header.

Lunawolfy · 2 Jul 2011 at 23:15

I'll need to have a look in the morning, I just want to step everything up +200 rpm. Try and squeeze a little more from the cooling

setter · 3 Jul 2011 at 10:09

If you take a look under hardware monitoring in the bios, youll find the chassis fan control options. If you turn off chassis fan control, the fans will run full speed all the time. Alternatively, leave it enabled and select the turbo profile, in windows use asus ai suite's fan expert to calibrate the fan speed settings, this will allow them to ramp up/down in speed.

Lunawolfy · 3 Jul 2011 at 10:10

UPDATE: Found the part in the BIOS where you can set manual fan control. I set the duty cycle +15% for <=40oC and the same for >=60oC

Idle spin is now 1300RPM

Jaffar · 3 Jul 2011 at 12:43

I have 4 antec tri-speed fans, which I leave on the lowest setting. Is there any way I can get my fans to automatically change speed? I think this would be quite handy. They're connected directly to my psu at the moment.

Lunawolfy · 3 Jul 2011 at 16:39

Jaffar said:
I have 4 antec tri-speed fans, which I leave on the lowest setting. Is there any way I can get my fans to automatically change speed? I think this would be quite handy. They're connected directly to my psu at the moment.

Not on the PSU. That just throws 100% Voltage at them all the time,

If connected to the mobo headers they would be under voltage control like mines.