Don't increase fan speed during idle when using a 3900X in a build with Noctua fans?
Don't increase fan speed during idle when using a 3900X in a build with Noctua fans?
I recently acquired my second desktop machine, which was entirely assembled by myself. The aim is to achieve the quietest possible operation. The specifications include a 3900X processor paired with a Corsair Vengeance LPX 32 GB (2x16) 3200 MHz motherboard, a Samsung 970 Pro Evo 1 TB SSD, and a B450-F Gaming Asus Rog Strix. The CPU cooler is a Noctua NH-D15, the case is Meshify C, and the fans are set to two NF-A14 PWM units for intake and one NF-A12x25 PWM for exhaust.
Initially, I ran everything in its default mode. The fans fluctuated frequently, not reaching extremely high speeds but constantly shifting between around 20% and 60% even when idle. Using HWMonitor, I observed the CPU temperature hovering between roughly 43 and 55 degrees Celsius. These spikes occurred within seconds, varying by up to 10 degrees, which was unexpected since I wasn't expecting such behavior. I assumed the changes were gradual rather than abrupt. The core voltages remained steady near 1.5 V.
After some research, I found that these temperatures were unusually high for a machine with minimal activity. It turned out others also experienced similar issues with the stock 3900X, confirming it wasn't due to incorrect thermal paste application. I suspected the problem might be distributed across the CPU rather than concentrated in one area. I wondered if the rapid heating of the CPU caused these fluctuations and how quickly the cooling system responded afterward.
Some suggestions suggested lowering the CPU voltage, but this seemed too advanced for a beginner. I began by tweaking the fan curves to allow the CPU to heat up before the fans activated, which helped reduce noise initially. However, the average temperature rose slightly back to around 50°C. I then attempted "EZ tuning" in BIOS, opting for "daily computing" and "tower cooler." This improved performance, with idle temps dropping to about 40%. Background processes still caused minor spikes up to 48°C, but the average fell by roughly 5 degrees. Idle voltages decreased to around 1.1 V. I also ran a fan calibration, which adjusted the lowest effective RPM and seemed to stabilize the fans better.
Despite these adjustments, occasional fan spikes persisted when using the PC at very low loads. I questioned whether further optimization was possible or if the system naturally required more airflow at idle. I wanted to maintain stability but avoid unnecessary noise unless the CPU was actively working.
I also realized that adding a "fan smoothing" feature of 15 seconds in BIOS might help, though its effectiveness remained unclear. After about 50 hours of use, I experienced a rare system freeze—Spotify looped for 200ms, and the screen froze completely. This was unusual and made me suspect CPU tuning could be involved. I noted that while individual core voltages were around 1.1 V, the overall "CPU core" reading on HWMonitor had risen to about 1.3 V, a change from the previous 1.5 V after EZ tuning.
This situation is still under investigation, and I remain cautious about making further changes until I confirm stability.
I rely on the Argus Monitor software to manage the fan settings in my system. It allows precise adjustments to keep the fans operating at specific conditions, preventing the fluctuations I encounter with most Asus BIOS options during light usage.
The tool lets me switch between letting the BIOS handle certain fans, applying fixed RPM values for others, and using software control for different fans or all of them—adjusting based on various temperature sensor inputs.
Additionally, you can set preferences for particular fans to respond to average or maximum temperatures, helping reduce sudden changes.
In the BIOS, pressing F6 will take you to the fan control screen. I would attempt to adjust the curve. Refer to section 3.2.3. https://dlcdnets.asus.com/pub/ASUS/...4....1576592336
Thank you for your feedback. The adjustments I made seem to reduce the fan's responsiveness, but it still fluctuates. I'm curious if this might be due to my motherboard's fan smoothing capabilities or if the temperature changes are too small for it to notice. Or could there be another issue at play?
I rely on a fan management program named Argus Monitor to manage the fan settings in my system. These settings are tailored to prevent the frequent adjustments I encounter with most Asus BIOS options when using light workloads.
I employ it to bypass standard BIOS configurations, allowing a blend of BIOS controls, manual RPM adjustments for individual fans, and software-driven management for others—adjusting based on various temperature sensor inputs.
It also lets you choose whether a particular fan should respond to average or maximum temperatures, and it defines the polling interval for each sensor’s temperature data.
You can obtain a complimentary 30-day trial with all program features available, so you can test if it addresses your needs.
Following the trial, a yearly license is priced around USD $9.99, with a more affordable three-year option.
The initial setup may take some time, but once complete, the software has proven highly effective.
I’m aware my system uses an Intel CPU and a Ryzen processor, both prone to temperature changes under light use, yet I remain confident you can find a configuration that reduces or eliminates the rapid fan speed shifts during light operation.
Since my 9900K tends to overheat, I also faced issues with inconsistent fan speeds and the resulting noise, which motivated me to move away from BIOS control and opt for software solutions to better suit my preferences.
Here’s a brief illustration of three distinct curves:
I apply different settings simultaneously for various fans. My idle/light load stays consistently below 46°C, with only minor spikes (to avoid sudden fan changes). At higher loads, it ranges from 50–65°C, and the maximum stress test sits between 66–74°C (except during Prime95 with AVX, which reaches 82°C).
The HI_AMP curve applies to top exhaust fans that spin up slightly under load, while the CHA_FAN2 curve targets front intake fans during cold air intake phases. I customize a curve for rear exhaust fans like CHA_FAN1 to align with CPU cooler RPM at high temperatures, aiming to enhance cooling efficiency and reduce pressure buildup between the rear exhaust and cooler.
There are numerous ways to optimize airflow and fan performance.
You can even store four different profiles to switch quickly, such as a gaming mode, a quiet steady-speed profile, and a high-performance setting.
It’s been beneficial to let chassis fans react not only to GPU but also CPU temperatures. This helps because some games impose minimal CPU load, so case fans wouldn’t spin much during gameplay—though this slightly increases GPU heat, reducing boost clocks and duration marginally.
Allowing intake and exhaust chassis fans to respond to GPU temperature has marginally improved gaming performance, which I appreciate.
I own five 140mm Noctua Redux PWM 1200RPM chassis fans and a Noctua NH-D15 Chromax.Black CPU cooler, all managed via the software referenced above (with two intake fans split by a Y-splitter).
Apologies for the lengthy explanation—I included details to ensure clarity, as it appears you’ve invested considerable time in your current configuration... I hope you discover a suitable solution for your desired fan behavior and noise levels.
Thank you for your feedback! This information is really helpful. I plan to explore Argus Monitor and see if it can improve my setup.
I also came across a video discussing 3.6 GHz and sub 1 V performance during idle with the 3900X, while my system runs at 1.1 V and 4 GHz at the lowest settings. It seems adjusting certain parameters might be necessary. The EZ tune preset in BIOS already helped lower temperatures, so I expect further improvements if that worked properly.
There's also a free software controller called
SpeedFan
which used to be very popular. But it hasn't been updated since 2015, and unfortunately the sensor chip and fancontroller on my motherboard, weren't supported by the current version of SpeedFan - but if your motherboard is supported, that could be a free alternative.
But I'm personally very satisfied with Argus Monitor, despite the fact that it isn't free to use.
EDIT : Updated with link