My PC has a liquid cooler in it with two ARGB fans, and an ARGB infinity mirror on top of the water block. I wouldn't have paid extra for the LEDs, but once I had them, I wanted them to do something. So I connected them to my ASRock motherboard, and played around with that functionality for a little while, but it turned out to have a serious deficit.
My B550M Phantom Gaming Riptide motherboard has ASRock Polychrome USB control for LEDs. This sounds like it should be awesome, but sadly the device doesn't support "direct" mode where you simply ask it to set the LEDs to a certain color. Instead, you save a setting to the LED controller, and then that setting is applied to the LEDs. This is a huge flaw, because that setting can only be saved so many times before you burn out whatever flash (best case) or EEPROM (worst case) it's written to.
Usually today an EEPROM is actually flash which pretends to be an EEPROM, so it has a fairly reasonable write lifespan, but it is still not infinite. If you write a new setting to this device as fast as possible at all times you use your computer, you will wear it out. It's weird to not have a direct mode in a USB-connected LED controller - in that case, why not put it on the SPI bus? - but it is what it is.
Enter nollie, a USB-connected ARGB LED controller which only has direct mode. At power on and before configuration, nollie emits a "breathing" green pattern; once initialized, it outputs only what you tell it. nollie comes in 1,8,16 and 32-port models, is supported by SignalRGB and OpenRGB, and comes with enough 5v 3Pin Female to Male adapters for all of its ports plus some transparent double-sided stickys for mounting whichever version you get. I got mine on aliexpress for ten dollars.
I was out of USB headers on my motherboard, so I also installed a non-powered USB 2.0 hub which was about $3. My nollie 8 and the hub both came with keyed two-row connectors; I moved the wires over to one of them and plugged the resulting cables into my board. The hub stuck onto a space in the basement of my case, which has one where the power supply and storage devices live; I installed nollie down there too. Each fan and the CPU LEDs got attached to their own outputs so they could be controlled independently.
The Hardware Sync plugin for OpenRGB allows you to control LEDs with sensors. After installing this plugin, I created one HWSync measure which drove all three of my LED zones to start with. I used the Tctl output from the k10temp driver. I was using a Ryzen 5 5600X at the time, so there was only one CCD, and its temperature changes a lot quicker than Tctl (the package temperature sensor) does, and this wound up being smooth. I didn't care for the default color scheme so I cooked up my own with four colors; Black at 20C, Blue at 35C, Green at 50C, and red at 90C. This gave pretty decent results. The black only really makes any visible difference when coming off idle (which is at about 30C) since the processor idles around 30C, and it heats up to that temperature long before OpenRGB loads.
Right after doing this, I upgraded to a 5900X. While the 5600X has one CCD with six cores on it, the 5900X has two, with six cores each. For some workloads involving few threads, the two CCDs on the 5900X have significantly differing temperatures. I've currently assigned Tctl to the CPU, Tccd1 to one fan, and Tccd2 to the other. It's blue at 40C, green at 55C, red at 90C, and I've added white at 95C.
Why bother with that last, when I've never a temperature over about 78C on any sensor? It's pretty cold in here right now so I don't know exactly what I'm likely to see when it's hotter, and the white is there just because I think there should be a sign of imminent failure just in case of emergency. The CPU will thermally throttle to protect itself as part of normal operation, and I have PBO ("Precision Boost Overclocking") turned on, which means that the processor will exceed normal power limits as long as it does not overheat.
The results are more visually pleasing than I at first imagined given the black-on-black-on-black "mess of cables" aesthetic that has dominated my computer, since there is practically no color in it. When the system is idle, all is blue. As work picks up, green starts creeping in, and for sporadic workloads it varies between the front and rear of the case. This is part of my view from the window side of the case, and I took the photo while the two CCDs were at significantly different temperatures so there's both blue and green.