FAQ
TL;DR: If your Zephyr 120mm reads 6,000 RPM, that’s a misread (stat), and “HWiNFO confuses the sensor readings” (quote). Diagnose by unplugging, cross‑checking headers, and consider replacing the FX‑6300 BOX cooler. [Elektroda, matikowy123, post #16626260]
Why it matters: This FAQ helps ASUS M5A78L-M LX3 and similar-build owners fix loud rigs, false RPMs, and case vibrations.
Quick Facts
- SPC Zephyr 120mm is rated around 1100 RPM; far higher readings indicate sensor or header mix‑up. [Elektroda, matikowy123, post #16625983]
- User-observed CPU idle reached 65°C after unplugging a case fan, with noise unchanged—points to the BOX cooler. [Elektroda, matikowy123, post #16626053]
- GTX 970 idle ~47°C; its fans typically ramp near 60°C, so idle noise likely isn’t the GPU. [Elektroda, matikowy123, post #16625983]
- Molex-connected case fans run at 100% without onboard adjustment. [Elektroda, badboy84, post #16626189]
- Reported: M5A78L-M LX3 lacked DC control for 3‑pin chassis fans in this build. [Elektroda, matikowy123, post #16626460]
Why does a 120mm case fan show 3,700–7,000 RPM in HWiNFO?
That speed is unrealistic for a 120mm case fan. The reading likely comes from the CPU fan but is labeled as Chassis. HWiNFO can misassign headers, so a “Chassis” RPM may actually be the FX‑6300 BOX cooler. Cross‑check with BIOS labels or ASUS Fan Xpert, if available. “HWiNFO confuses the sensor readings.” [Elektroda, matikowy123, post #16626053]
Can the SPC Zephyr 120mm really spin at 3,700–7,000 RPM?
No. The Zephyr 120mm is rated about 1100 RPM, so multi‑thousand RPM readings point to a sensor/header mix‑up. Verify which header the fan uses and compare with BIOS monitoring to confirm. Replace any mislabeled entries in your monitoring tool. [Elektroda, matikowy123, post #16625983]
How do I quickly find which fan is making the noise?
Use an elimination test: briefly unplug a suspected case fan and power on to compare noise. If loudness stays the same, the culprit is likely the CPU cooler, not the chassis fan. Restore connections before stress testing. This approach isolated the FX‑6300 BOX cooler in the thread. [Elektroda, barteksmrek, post #16626021]
My idle CPU hit 65°C after unplugging a case fan—what does that imply?
If idle rises to ~65°C with no change in system noise, airflow loss increased temperature while the primary noise source remained unchanged. That points to the CPU cooler. Restore airflow and service or replace the FX‑6300 BOX cooler to reduce temps and noise. [Elektroda, matikowy123, post #16626053]
Should I connect case fans to the motherboard or Molex?
Molex runs at 100% and offers no software control. Motherboard or a front‑panel controller allows voltage/PWM regulation. If you need quiet at idle, prefer header or controller connections. “The fan connected to MOLEX works at 100% and there is no adjustment option.” [Elektroda, badboy84, post #16626189]
Does the ASUS M5A78L-M LX3 control 3‑pin case fans?
This build reported no DC control for 3‑pin chassis headers, so 3‑pin fans stayed unregulated. If your board lacks DC support, use a PWM fan, a fan controller, or a 3‑pin to Molex adapter accepting fixed speed. [Elektroda, matikowy123, post #16626460]
What’s the difference between PWM and 3‑pin DC control?
PWM uses a fourth pin with a duty signal for precise speed control. 3‑pin DC varies voltage to change RPM, but only if the board supports voltage mode. As one expert noted, DC works, “but not every board supports this solution.” [Elektroda, Kasek21, post #16626444]
Is my GTX 970 likely the noise source at idle?
Unlikely, if it idles near 47°C and its fans only ramp around 60°C. At rest, the GPU fan should be slow or off, so focus on CPU cooler or case fans for idle noise and vibration. [Elektroda, matikowy123, post #16625983]
Why does my PC vibrate through the floor at idle?
A loud or unbalanced CPU stock cooler can resonate through the chassis and floor, especially on rigid surfaces. In the thread, strong vibrations remained even at rest, pointing to the FX‑6300 BOX cooler rather than case airflow. [Elektroda, matikowy123, post #16625983]
How can I confirm HWiNFO mislabels CPU and Chassis fan headers?
Perform a quick isolate test: disconnect the chassis fan, boot, and check which RPM reading disappears. If “Chassis” remains and changes with CPU load, the CPU header is mislabeled as Chassis in software. Then adjust your monitoring tool’s labels. [Elektroda, matikowy123, post #16626053]
Give me a 3-step how-to to diagnose the loud fan.
- Unplug the chassis fan temporarily and boot; note noise and temps.
- Watch HWiNFO/BIOS to see which RPM changes; relabel if needed.
- If noise persists, service or replace the FX‑6300 BOX cooler and retest. [Elektroda, matikowy123, post #16626053]
What is a fan controller and why use one?
A fan controller is a front‑panel or in‑case module that powers multiple fans and lets you adjust speeds by knobs or switches. It centralizes control, handy when motherboard headers are limited or lack DC/PWM features. Example: Gladius X60’s built‑in controller. [Elektroda, badboy84, post #16626220]
Can positive pressure reduce dust in my case?
Yes. Slight intake bias helps push air out gaps, limiting dust ingress. Pair it with intake filters for best results. One builder maintained low overpressure and used electrostatic filters to trap dust effectively. [Elektroda, barteksmrek, post #16626229]
I only have 3‑pin fans but no adapters—can I still run them?
Yes. You can connect 3‑pin to motherboard headers for reading/control if supported. Without adapters, they won’t run from Molex directly. A 3‑pin‑to‑Molex adapter or a controller enables power and fixed or manual control. [Elektroda, matikowy123, post #16626260]
Edge case: Could software swap CPU and chassis readings?
Yes. The thread shows CPU RPM reported under the Chassis label, creating false 6,000 RPM case fan readings. Always cross‑verify with BIOS labels and a simple unplug test before replacing parts. [Elektroda, matikowy123, post #16626260]
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