No RPM signal detected from TH420 Ultra ARGB Sync fans

[RayBull]

 

Hi, I'm using the Thermaltake TH420 Ultra ARGB Sync AIO (model CL-W386-PL14SW-A)

and experiencing issues with fan RPM detection and software control.

 

 

 

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🧰 My system setup:

• CPU: Intel Core Ultra 9 285K (LGA1851)

• Motherboard: ASUS ROG STRIX Z890-E GAMING WIFI

• RAM: G.SKILL Trident Z5 RGB DDR5-6000 

• GPU: MSI RTX 4070 Ti SUPER Gaming Slim

• PSU: ASUS ROG STRIX 1200W Platinum (ATX 3.1)

• OS: Windows 11 Pro 64-bit

• Case: Thermaltake View 71 TG RGB

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⚠️ The problem:

• I connected the three 140 mm radiator fans in daisy-chain (4-pin PWM) to the CPU_FAN header, but:

  • BIOS shows “N/A” for CPU_FAN RPM.

  • No RPM signal is detected, despite all fans spinning normally.

• I confirmed that PWM mode is set in BIOS (not Auto).

• As a temporary fix, I moved the pump to CPU_FAN, which correctly reports ~3200 RPM, and moved the fans to AIO_PUMP. This prevents the BIOS warning, but doesn’t solve the real issue.

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❌ TT RGB PLUS Software issue:

• The TT RGB PLUS app (latest version):

  • Detects the LCD screen and allows me to customize the display (CPU temp, colors, brightness).

  • But does NOT detect any controller or fans.

  • Tabs for “Controller” and “Fan speed” show the standard warning: “No controller detected”.

• USB header is connected to the motherboard and works.

• Device Manager shows no unknown USB devices.

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❓ Questions:

1. Do any of the fans in this AIO actually transmit an RPM signal?

2. Is daisy-chaining the fans supported, or should I use a proper PWM splitter?

3. Is this AIO expected to support fan control from TT RGB PLUS, or only through BIOS?

4. Is there any firmware or driver required for fan control detection in the app?

5. Can Thermaltake confirm the correct connection layout for BIOS + software control?

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Thanks in advance for your help! I'd like to get full PWM control from BIOS or the TT software if possible. Everything else (pump, LCD, temperatures) works great — only fan control is missing.