(Satellite Radius P55W-B5224) CPU fan not running or recognized.

Hi @secondlife ,

Bit hard without a schematic of the motherboard but I suppose you have to start somewhere and prove if there is power or earth being supplied to the fan from the motherboard's CPU fan header pins. (obviously one or the other is not being supplied, as the fan works externally).

I'm wondering as it is a 3 wire fan the BIOS may be expecting a signal to indicate that the fan is operational either by the fan sending a rpm signal (hall effect sensor) or a temp signal (thermistor) on the "sense" (white?) wire from the fan

I'm hoping that it is a thermistor so check if there is a resistance reading between the earth wire (black) and the "sense" (white) wire from the fan. You could try heating the fan with a hair dryer and check if the resistance reading alters to prove it is a thermistor.

If there is a no resistance reading on the sense wire due to a faulty thermistor say, it may be that the power to the fan is not being turned on as there is no fan being detected. This is just speculation on my part however. Have you got another 3 wire fan that you can check if there is a resistance value between earth and sense? It doesn’t have to be the same value just that there is one.

Try searching online for (insert motherboard’s board number) schematic, hopefully there may be one available which would make life so much easier

Also wondering if the "thermal" error message problem you mention at the end is perhaps an inbuilt CPU temp sensor detecting that the CPU is getting too hot, assuming that the fan is removed from the CPU and the heat sinks aren't there