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Can't get PWM fan curve steep enough

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SMOKEU

Member
Joined
Nov 7, 2010
Location
NZ
I have 3 Noctua 140mm PWM case fans connected to the Gigabyte GA-AB350M motherboard fan headers in PWM mode. The fans have a maximum RPM of 1500. I'm using the motherboard case temperature sensor.

I can't get the fan curve steep enough either in the UEFI or with the Gigabyte SIV. I would like to have the fans spinning as slow as possible (around 350RPM at 20%) when the case temperature is below 40C, and then 100% at 46C. This would be perfect as I want the fans spinning slow to reduce the insane amounts of dust this thing sucks in even with dust filters, but I want the fans to spin fast when it warms up.

I don't want to completely stop the fans as I need extra airflow over the motherboard VRMs and the SSD.

I simply can't get the curve steep enough. What can I do?

View attachment 209848
 

Zerileous

Senior Member
Joined
Jun 21, 2002
First thing I would try is getting rid of all the extra steps, so just one at 20% at your starting temp and another at 100% as far left as you can get it. Does the delta temperature interval slider change the pitch of the curve?

I'm not sure why you want such a curve though, to me it would make more sense to have a flatter curve, 40c is more than you really want your case temp to be IMHO.
 
OP
S

SMOKEU

Member
Joined
Nov 7, 2010
Location
NZ
Even if I get rid of those extra steps, that still doesn't allow me to increase the steepness of the curve.

With the fans at 350 RPM, the case temperature is usually around 35C - 38C in a 22C room under idle or very light use. Intense gaming sessions will push the case temperature to around 46C - 47C at 1300 RPM.

With the fan curve adjustments I have, I have to either settle for quiet but relatively hot operation under heavy load, or I have to have the fans spinning at 700 RPM minimum which brings in a huge amount of dust.
 

Zerileous

Senior Member
Joined
Jun 21, 2002
based on what your telling me, you could have your curve from 35c to 45c or 50c. Looking at your screenshot, I see a red dot under the top PCIe slot on the motherboard graphic. Is this the senor location? If so it will be very sensitive to GPU temperature and maybe not an accurate reflection of case air temp. What are your component temps at 46/47c and 1300 RPM. Maybe you have more headroom than you think.
 

BugFreak

Joined
Apr 29, 2010
Location
Central FL
My ASUS fan controller has the same problem. I finally settled on fairly close to what I wanted and figured it is a limitation of the software. There is also a minimum starting/spinning speed for the fan that has to be considered.
 

Dr_Emmett_Brown

Registered
Joined
Apr 22, 2020
Location
Caprona
If possible, try and get the settings to correspond to the dedicated "CPU Fan" item in the controller, and dongle all 3 fans together in series. That way, the most mission-critical temperature will be the driving force of the cooling. Otherwise, the most likely outcome will be seemingly random "fan speed throttling," going from very high speed to near idle and vice versa often enough to be really annoying.
 
OP
S

SMOKEU

Member
Joined
Nov 7, 2010
Location
NZ
based on what your telling me, you could have your curve from 35c to 45c or 50c. Looking at your screenshot, I see a red dot under the top PCIe slot on the motherboard graphic. Is this the senor location? If so it will be very sensitive to GPU temperature and maybe not an accurate reflection of case air temp. What are your component temps at 46/47c and 1300 RPM. Maybe you have more headroom than you think.

Yes, I believe that's where the temperature sensor is as shown in that diagram. Under heavy gaming when the case temp is at 46-47C, the GPU will be around 75-80 and the CPU around 60-70.

If possible, try and get the settings to correspond to the dedicated "CPU Fan" item in the controller, and dongle all 3 fans together in series. That way, the most mission-critical temperature will be the driving force of the cooling. Otherwise, the most likely outcome will be seemingly random "fan speed throttling," going from very high speed to near idle and vice versa often enough to be really annoying.

I did consider that but what if I'm running something GPU heavy that doesn't stress the CPU much? I'm thinking then the CPU temperature might not get hot enough for the fans to ramp up enough. I guess it's a compromise.
 

trents

Senior Member
Joined
Dec 27, 2008
Can you store profiles in the bios? Make one for apps that are heavily CPU intensive and one for apps that are GPU intensive.