CPU Opt fan always running at 100%

Zukker

n00b
Joined
Sep 27, 2008
Messages
31
Hope you can help me.

I have ASUS Z87-A motherboard paired with a i5-4670K and a Cooler Master 212 evo cpu cooler. I had just one fan on the cooler and had temps of around 30o C. I decided to put a second fan on the cooler in a push-pull configuration to hel keep temps low from on a 4.2 GHz overclock. I bought 3 pin Cooler Master 120 mm fan and installed it. The idle temp are now at 25oC and game temps at 56oC. So far so good.

However the new CPU fan always runs at 1800 RPM. I can not get it to change RPM due to load. I did run ASUS's fan utility and the new fan shows up.

Should I have bought a 4 pin fan? Would that solve the non-changing RPM on the fan?
 

mda

[H]ard|Gawd
Joined
Mar 23, 2011
Messages
1,859
If this helps, the Opt fan on my Z87 Pro is always running full speed as well. Ended up moving the fan to the rear exhaust.
 

thebski

Limp Gawd
Joined
Mar 7, 2012
Messages
336
Hope you can help me.

I have ASUS Z87-A motherboard paired with a i5-4670K and a Cooler Master 212 evo cpu cooler. I had just one fan on the cooler and had temps of around 30o C. I decided to put a second fan on the cooler in a push-pull configuration to hel keep temps low from on a 4.2 GHz overclock. I bought 3 pin Cooler Master 120 mm fan and installed it. The idle temp are now at 25oC and game temps at 56oC. So far so good.

However the new CPU fan always runs at 1800 RPM. I can not get it to change RPM due to load. I did run ASUS's fan utility and the new fan shows up.

Should I have bought a 4 pin fan? Would that solve the non-changing RPM on the fan?
You need a 4-pin fan to have motherboard speed control. Fan controllers can control the speed of 3-pin fans by changing the voltage to them and thus the speed, but motherboards only control via PWM (4-pin). In addition, the two fans need to be plugged into the same type of fan header. Your board likely has CPU_fan, OPT_fan, and CHA_fan headers that each have different speed profiles (usually adjustable in bios or with Asus Fan Expert). Hope this helps.
 

Zukker

n00b
Joined
Sep 27, 2008
Messages
31
You need a 4-pin fan to have motherboard speed control. Fan controllers can control the speed of 3-pin fans by changing the voltage to them and thus the speed, but motherboards only control via PWM (4-pin). In addition, the two fans need to be plugged into the same type of fan header. Your board likely has CPU_fan, OPT_fan, and CHA_fan headers that each have different speed profiles (usually adjustable in bios or with Asus Fan Expert). Hope this helps.

Thanks for your reply.

Although I see the CPU Opt fan in ASUS Suite III Fan expert. there is no way, that I can see, that will allow me to adjust the CPU Opt. I can fully adjust the "normal" CPU fan. I do have the latest BIOS rev and the ASUS Suit III version as well.

I will try to get a 4-pin fan and see if it makes any difference. The good news is that I have dropped game temps by about 5 oC so it does work, just trying to reduce the wear and tear on the fan bearings.

Thanks once again!
 
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