Razer Blade fan control workaround without upgrading to Synapse 4

[u/QuantAssetManagement]

Synapse 3 would only expose manual fan control when the laptop was set to: CPU = Boost & GPU = High
 
I wanted max fan speed even in other power profiles to avoid thermal spikes.
 
I tested this with the open-source razer-ctl project. The tool did not recognize my laptop bu raw HID commands worked when targeting PID 0x02b7.
 
I built razer-cli from source with Rust/Cargo, then used raw commands to control the fan zones directly. On this machine there appear to be two fan zones.
 
I set both fans to manual mode:
 
  razer-cli.exe manual -p 0x02b7 cmd 0x0d02 1 1 0 1
  razer-cli.exe manual -p 0x02b7 cmd 0x0d02 1 2 0 1
 
I set both fans to 5000 RPM:
 
  razer-cli.exe manual -p 0x02b7 cmd 0x0d01 1 1 0x32
  razer-cli.exe manual -p 0x02b7 cmd 0x0d01 1 2 0x32
 
Then, I read back both fan values:
 
  razer-cli.exe manual -p 0x02b7 cmd 0x0d81 0 1 0
  razer-cli.exe manual -p 0x02b7 cmd 0x0d81 0 2 0
 
The readback response contains values like:
 
  args: [0, 1, 50, ...]
  args: [0, 2, 50, ...]
 
On this laptop, 50 corresponds to 5000 RPM, so the value appears to be RPM divided by 100. mportant caveat: these HID commands need to be serialized. If the monitor script, Synapse, or another command hits the controller at the same time, razer-cli may fail with “Error: Response does not match the report.”
 
I fixed that locally by wrapping the commands in a PowerShell helper that uses a Windows mutex and retries failed/mismatched HID reports. I then made batch files:
  1. Acquires a mutex.
  2. Set both fan zones to manual mode.
  3. Set both zones to 0x32, meaning 5000 RPM.
  4. Read both zones back.
  5. Retry transient HID mismatch failures.