I doubt most user have any need for great nc performance.

I also doubt those “super performant nextcloud flakes” are actually any faster than a plain old default nc deployment; especially for our use-cases.

Using NixOS is a good recommendation though. Just don’t do flakes unless you actually understand what problem they intend to solve and how catastrophically bad they are at it.

First of all you need to figure out which sensor this even is. On my nct6687, there’s a sensor on the PCIe slot that is constantly >90° and that appears to be totally normal.

Could you post the output of sensors?

Here is how it looks like on my machine:

nct6687-isa-0a20
Adapter: ISA adapter
+12V:           12.26 V  (min = +12.14 V, max = +12.46 V)
+5V:             5.06 V  (min =  +5.00 V, max =  +5.08 V)
+3.3V:           0.00 V  (min =  +0.00 V, max =  +3.40 V)
CPU Soc:         1.02 V  (min =  +1.02 V, max =  +1.04 V)
CPU Vcore:       1.27 V  (min =  +0.91 V, max =  +1.40 V)
CPU 1P8:         0.00 V  (min =  +0.00 V, max =  +0.00 V)
CPU VDDP:        0.00 V  (min =  +0.00 V, max =  +0.00 V)
DRAM:            1.11 V  (min =  +1.10 V, max =  +1.11 V)
Chipset:       202.00 mV (min =  +0.18 V, max =  +0.36 V)
CPU SA:          1.08 V  (min =  +0.61 V, max =  +1.14 V)
Voltage #2:      1.55 V  (min =  +1.53 V, max =  +1.57 V)
AVCC3:           3.39 V  (min =  +3.32 V, max =  +3.40 V)
AVSB:            0.00 V  (min =  +0.00 V, max =  +3.40 V)
VBat:            0.00 V  (min =  +0.00 V, max =  +2.04 V)
CPU Fan:        730 RPM  (min =  718 RPM, max = 1488 RPM)
Pump Fan:         0 RPM  (min =    0 RPM, max =    0 RPM)
System Fan #1:    0 RPM  (min =    0 RPM, max =    0 RPM)
System Fan #2:  490 RPM  (min =  421 RPM, max =  913 RPM)
System Fan #3:    0 RPM  (min =    0 RPM, max =    0 RPM)
System Fan #4:  472 RPM  (min =  458 RPM, max =  939 RPM)
System Fan #5:    0 RPM  (min =    0 RPM, max =    0 RPM)
System Fan #6:    0 RPM  (min =    0 RPM, max =    0 RPM)
CPU:            +37.0°C  (low  = +30.0°C, high = +90.0°C)
System:         +25.0°C  (low  = +22.0°C, high = +48.0°C)
VRM MOS:        +22.0°C  (low  = +20.5°C, high = +66.0°C)
PCH:            +21.5°C  (low  = +18.5°C, high = +49.0°C)
CPU Socket:     +21.0°C  (low  = +19.0°C, high = +56.5°C)
PCIe x1:        +92.0°C  (low  = +76.5°C, high = +97.0°C)
M2_1:            +0.0°C  (low  =  +0.0°C, high =  +0.0°C)

Note that I use the https://github.com/Fred78290/nct6687d/ kernel module though. The upstream one doesn’t label many temps.

In this comparison, the devil is in the detail.

With Ansible, you have an initial condition onto which you add additional state through automatically executed steps dictated by you until you (hopefully) arrive at a target state. This all happens through modification of one set of state; each step receives the state of the previous step, modifies it and passes the entire state onto the next step. The end result is not only dependant on your declared steps but also the initial state. A failure in any step means you’re left in an inconsistent state which is especially critical for the case of updating an existing state which is the most common thing to do to a Linux system.

In NixOS, you describe the desired target state and the NixOS modules then turn that description into compartmentalised bits of independent state. These are then cheaply and generically combined into a “bundle”; wrapping them into one big “generation” that contains your entire target state.
Your running system state is not modified at any point in this process. It is fully independent, no matter what the desired system is supposed to be. It is so independent in fact that you could do this “realisation” of the NixOS system on any other system of the same platform that has Nix installed without any information about the state of the system it’s intended to be deployed on.
This “bundle” then contains a generic script which applies the pre-generated state to your actual system in a step that is as close to atomic as possible.
A good example for this are packages in your PATH. Rather than sequentially placing the binaries into the /usr/bin/ directory as a package manager would when instructed by ansible to install a set of packages, NixOS merely replaces the bin symlink with one that points at an entirely new pre-generated directory which contains the desired packages’ binaries (well, symlinks to them for efficiency). There cannot possibly be an in-between state where only some of the binaries exist; it’s all or nothing. (This concept applies to all parts that make up a Linux system of course, not just binaries in the PATH. I just chose that as an easy to understand example.)
By this property, your root filesystem no longer contains any operating system configuration state. You could wipe it and NixOS would not care. In fact, many NixOS users do that on every boot or even use a tmpfs for /.

(Immutability is a property that NixOS gains almost by accident; that’s not its primary goal.)

meaning every step of building the kernel, including the steps taken to build the C compiler toolchain, are produced by code that is simple enough to check for correctness and safety.

Full-source bootstrap isn’t about just the kernel, it affects every piece of software. With GUIX and Nix, every single package can be fully traced back to the bootstrap seed.

Though it should be noted that you do require a running Linux kernel on an x86 machine in order to bootstrap.

it is not quite to the point where it /just works/ on a lot of the computer hardware that I own.

Unless we get some serious money, effort and/or regulation w.r.t. OSS firmware, that will likely never be the case.
That has nothing to do with its technology though, that’s a political issue. GUIX is a GNU project and acts like proprietary software does not exist/is not a basic necessity in 2023.

Sounds like your flatmate should invest in a lawyer. That company probably owes them a ton of money.