How does the EC determine what fan speed to use?

IIRC clevo motherboards have no fan controllers so you cant set fan speeds using something like speedfan, and the fans are controlled by the EC.

How does the EC know what fan speed to use for what temperature? Does it check the temperature sensor on the motherboard? If yes, is there any way to confirm whether the temperature sensor is working properly?

 

to my knowledge it's a closed loop hardwired system. A PWM signal is fed to the fan based on the input from an Embedded Controller, this EC draws it's data from onboard sensors (usually a separate direct motherboard thermal diode instead of the Intel DTS though some machines use the average value) and refers to a pre-programmed (usually also reprogrammable) lookup table (e.g. 40 degrees, run at 1200RPM, 50 degrees, run at 1800RPM etc etc) stored within an EEPROM. The EC then usually polls the sensory data at specific intervals (judging by the average response speed on the Clevo laptops I've owned, it is every few seconds) and thus makes adjustments accordingly.
Basically, it is all hardwired.
I have a HP DV6-3032Tx that also uses this system, however, the EC sensor can be overidden, basically, HP decided it was a bad idea to put an i7-720QM in a slim laptop so to address the overheating concerns, they simply reprogram the EC sensor to be 85 degrees at all times regardless of the Intel DTS on a BIOS update. The overheating was fixed but the fan basically never spins down, thankfully, the EC also allowed direct software reprogramming so I was able to use HwInfo to customize the lookup table.

 

Okay but how do you know if the correct temperature is being given to the EC?

IIRC, the Clevo EC doesnt allow software reprogramming?

 

You can't intercept it or read out values if that's what you mean. You can only look for symptoms like high fan speeds with low temperatures or system panics when nothing is wrong.

 

To answer the OP's specific question, the only indication that you'll receive if sensor data is not accurate would be if you're experiencing unexpected fan response. I can't get into too much detail because ultimately the EC is not an open controller, but the best way to look at it is this; you're as likely to get an inaccurate sensor input into the EC as you are to experience an inaccurate CPU or GPU temp sensor reading directly from the component.

When we are designing or optimising our XMG EC, we use the sensor input similarly to how Marksman30k described, but as I mentioned previously it's more complicated depending on the chassis and the number of data sources and fans that need to be controlled.

 

Well i have been noticing odd fan behaviour lately. For example even though the laptop is below 50 degrees celsius, the fan is spinning at a much higher speed than before and making a lot of noise as a result....

Is there any way to fix it? Where is the EC located exactly?

 

I believe in the keyboard controller. You flash it with the bios so you could try updating it.

 

If it's a newish laptop then contacting the company you purchased it from should be the first port of call. New models have power settings in the Hotkey driver software, but it depends on your model.

Flashing the EC to a newer version can be tried, but this is unlikely to solve a fan speed issue unless there is an existing bug in the version you are already using. There's lots of variables here and it's much more likely that there is another force at play, for example your fan may be getting old and making more noise rather than it actually running faster; the fan may be running faster than normal because the GPU temperature is higher, rather than the CPU temp being higher and so on.

 

@mySN.de, I noticed that you have a new EC firmware for W504, is that optimized by mySN or is it just a stock clevo EC firmware?

 

Like he said the newer models use stock ECs as Clevo put the suggestions they made for their older custom ones into place for the newer stock ones...

 

Actually, I didn't say that and it's not stricktly true either

steberg - I would recommend you contact the XMG office that you purchased your laptop from and ask them if the latest EC has any benefits for you over your current one (make sure you give them your current BIOS and EC version)

 

Well, Clevo used your custom P1xxSM (non-A) EC values and suggestions and based their stock P1xxSM-A ECs on them...which is actually a huge improvement, an achievement from your end and a good thing for all Clevo user! :hi2:
(Not sure about other models. I shouldn't have generalized! I simply checked the one the user asked for and "your" P1xxSM-A ECs are identical to Clevo stock ECs > they are a 100% diff match in hex):

Spoiler

 

We were pretty pleased with the P1xxSM improvements, thanks for the comments and happy to hear that the work is appreciated by our friends and other Clevo owners:hi2: