My PC 8 years ago when it was first built, and today.
GPU's upgraded numerous times, and a better sound card installed.
Only other changes to hardware are the AIO cooler (the H100 started leaking a few months ago) and replacement fans due to dead bearings.
HDD's moved to allow better airflow over the GPU's, a bit of cardboard in the drive bays holding an additional intake fan in position.
The main thing I noticed though was that my LED lighting actually used to be quite bright, whereas now you can barely tell it is on, even at night.
The plastics in the case are also very brittle now, and will snap if you try and flex them at all. (Including clips and other things that are meant to be flexed) and the inbuilt fan controller has completely died.
It is on almost 24/7, only switched off when the power has to be turned off, and when dusting or upgrading it. I figured out that it has roughly 68,000 hours of up-time. Over half of those 68,000 hours have been at a significant load percentage, either gaming, folding, or mining.