I have a Gigabyte EX58A-UD3R rev2 mainboard, which has around 50 leds (in groups of around 5-6) that Gigabyte's windows utility uses to report CPU/DRAM/NB/SB loading, voltages, frequencies and temperatures. Both frequency and voltage leds work in windows and linux (and BIOS, memtest etc) so I imagine they're directly hardware controlled with no software 'interface', but the temperature and load leds are driven using the Gigabyte DES2 utility (Dynamic Energy Saver 2 - marketing crap) which means that they must be drivable using software.

I have asked Gigabyte for as much information as they'll give me, but I'm not expecting much, so I was wondering if there was a way of probing for these leds? Or possibly reverse engineering the DES2 utility?

Google hasn't thrown anything up, and I'm a bit wary of just poking at random GPIOs, so does anyone have suggestions of where I should start looking?

Many thanks

So why do you want to play with the motherboard leds? Most people run their systems with the box shut so the leds aren't visible? If you want to monitor hardware stuff while Linux is running; CPU speed, net activity, temperature of each core, main board and GPU, etc why not use a utility like GKrellm?

My

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I have not had much experience with 64 bit main boards but in the "bad old days" LEDs were used for "post code" errors on a main board which are tied through software and hardware to the BIOS to report when some part of the PC went wrong. 8 LEDs would stop at an 8 bit code if startup did not complete and if all of the lights went out there was no problem BIOS wise and the PC would load the OS.
I have no idea why a manufacturer would go to the expense of that many LEDs now, but my guess is that they are still being used for post operations. Dell only has one LED and it is serially flashed to report codes.
Post codes (and the routine to flash the leds) was located in the BIOS ROM. I would imagine you will find the code in the flash memory of your main board, but I have no clue as to reading the flash code. You could see if a BIOS file is available for your board and take a look at it if you don't mind looking through a lot of hex code.

The LEDs are visible in windowed cases, and in a windows environment at least, it can be quite useful since there is little win software around that monitors temps/loadavr/voltages/frequencies - especially useful for overclockers too.

The frequency and voltage leds are driven by the BIOS afaict, but I've not been able decipher the BIOS yet. There is a (single) separate POST LED, driven off the same output as the pc speaker... The board is multilayer, so finding the traces to/from the LEDs/nearby ICs has not been successful.

Just started looking at reverse-engineering the windows utility...my God it's bad. Mostly written in MS Visual C++ Studio, some in C#, covered in amusing misspellings, and it looks like it writes 327bytes to disk every program cycle :S Not great for a power-saving utility... Although, to be fair, lighting up 50 LEDs can't help power consumption a great amount...

So, aside from the above, I've looked through the BIOS hex dump, the acpi tables, and I'm gonna try googling every single IC on the board to find something... Any other suggestions?

As I said before, try GKrellm, it can report most of these things mentioned, you just add modules as required and it displays all in a neat little column which you park out of the way on your desktop. Why re-invent the wheel? As this is a Linux forum I assume you're using this OS?

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Indeed, linux is my main OS, and I use lm_sensors/conky/applets etc to monitor stuff, while there's a monitor attached. I was just explaining why I thought gigabyte might choose to spend money on leds.

When running headless, those leds are the quickest way of checking up on the hardware, and besides - if windows can drive them, I want to too! :P

Any motherboard leds tend to be controlled by the hardware on the board, i.e. are OS independent. They're used to fault find when the system won't boot an OS. (I repair Sun, IBM & HP servers for a living) The Gigabyte utility used under Windows is used to monitor the motherboard status, not control the leds.

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Indeed, usually that is the case. However, these LEDs are specifically intended to show processor/dram/nb/sb voltages, temperatures, frequencies and loading. Two sets of LEDs (voltage and frequency) are OS agnostic - they're on whenever the machine is powered up, windows, linux, BIOS, memtest etc... the temperature and loading LEDs however are only lit when the DES utility is running - therefore they are at least enabled through userland software. As well as monitoring, the DES util plays with LEDs (including the system power LED too... hmm, I think I've seen somewhere to control that one in linux), and can control the voltages and BClk (to some extent).

Reeet, from what I can see, the DES utility enables and drives some gpios, so I need to find out which gpio ICs are used, if there are linux drivers for these chips, and what the port numbers are... I don't seem to be able to poll each possible port to find the right ones either