Reading more voltages on an ASUS laptop based around HM76?

[rcx]

What is required to be able to read more voltages on a specific ASUS laptop? The only thing that shows is the CPU voltage. I guess voltages aren't reported by the HM76 chipset. Is there any way I could try to figure out the sensor chip mapping? Is the same chip responsible for fan speed reporting?

 

[Martin]

Almost all notebooks use a special chip called Embedded Controller (EC), which is responsible for fan control and monitoring of certain values. They usually monitor temperatures and fan speeds and just very few of them monitor voltages too.
The problem with these ECs is, that they run their own proprietary firmware, for which the vendors don't release any information. So it's not possible to support (most of) them.

Desktop PCs on the other hand use an LPC/SIO or dedicated hardware monitoring chip which in most cases is well described and can be supported.

 

[rcx]

Is there another element that monitors voltages, or are voltages just not generally monitored on notebooks?

I read the other thread about the Clevo laptop. Any idea how the information was revealed in that case?

Is it possible that voltage reading is implemented in the BIOS, just not visibly enabled? If so, how likely it is that BIOS reverse engineering could help find the needed info?

 

[Martin]

I don't think that on most notebooks voltages are monitored - there are simply no circuits implemented for such tasks.
Regarding Clevo notebook ECs, I think some guys found that information experimentally by watching EC registers and fan speed levels. But this is just my pure guess...

 

[rcx]

That's odd. You'd think laptops, as more highly integrated machines with more constraints on power and temperature, would have more need for precise monitoring and control. Any idea why, in fact, voltages are monitored on desktop boards?

 

[Martin]

Laptops are not as modular as desktops are - you cannot change the PSU, or other items with such a variety of components.

 

[rcx]

Thanks the info.

 

[rcx]

Hey. I noticed a recent version has "Enhanced sensor monitoring on ASUS A55M series". What does it include? Would it apply to a K55? I suspect they're very similar models.

 

[Martin]

ASUS A55M series are desktop mainboards, so this doesn't have anything to do with notebooks.

 

[rcx]

Oh. There are also A55* laptops, the last letter is usually just a variant.