If you know you know

I have a tradition of only using my old system or systems I've been gifted or outright found in the ewaste as a lab pc. All it has to do is provide me with a browser, a pdf viewer, some chat programs, and the odd specialized program. The more I/O options it has, the merrier. The more drive bays, the better. Recently I've been given a Lenovo OEM i7-6700 box by a friend. Great, I thought. Time to send the old Sandy Bridge system into retirement, a bit of an upgrade. I'll transfer the board into the old case, since it has much more room and is only half as ugly .. but oh god, Lenovo why

These are the Power connectors coming from the PSU (top), and going to the drives (bottom). Yes, they reduce the wire mess not with modular wires plugged into the PSU itself, but the board. And of course the main connector is proprietary bullshit. And of course the PSU is anemic af and doesn't provide enough power connections even for a half way decent graphics card.

But now comes the real kicker. The fans were running incredibly loud. Fan speed management is something of the 2000s, I didn't expect that to be an issue. So I checked the BIOS and all is fine there. Yet, the fans were in jet engine mode

No problem, I'll just throw lm-sensors and pwmcontrol at the problem. How hard can it be? Done it before. Over a decade ago, lol.
sensors-detect told me there is an nct668x IC, with the required kernel module being nct6683. Alright, let's try pwmcontrol .. huh, permission denied?

So, not only were those I/O devices set to read only, writes have no effect

Some of the register locations can be reverse engineered; others are too well hidden. Given this, writing any values from the operating system is considered too risky with this firmware and has been disabled. All limits must all be written from the BIOS.

https://docs.kernel.org/hwmon/nct6683.html

And of course, there is no parameter to override this. Let me burn my hardware down if I want to!

So what gives?
Having a look at the actual sensor readings gave me a clue.


Of course the BIOS' own control algorithm gets angry when one of the sensors reports 120°C

I scored so much stuff at the Finger Treffen hacker camp, it will take a while for me to digest it all.

Thanks Panda and Keyjn, for putting up with me

Let's start with these. I rescued all three logic analyzer and this pattern generator from certain destruction. One is already with a new, happy owner, and known working

In the box of LA probes and parts were these. 64 pin IC clamp, damn. That will come in handy for classic 68k stuff