An update from my previous media PC, with much more power under it now.

Some time ago I swapped out the CPU cooler and PSU. The stock cooler was fine, but I wanted something a bit more quiet so a Hyper 212 was overkill but quiet overkill. I swapped in a Be Quiet 500W unit, I had it laying around and it was much quieter than my previous Corsair unit.

Recently I added a bunch of things to make it quieter / more powerful.
I added an extra intake fan for better cooling.
I added an AMD RX 470, I noticed my integrated graphics sometimes struggling with 4K60 footage and video, so I thought this 470 I recently got would fix that (and it did!).
I swapped the ram with a slightly slower kit, mostly because I wanted to free the kit that was in this PC. DDR4 3000 mhz CL16 is still plenty fast.
I swapped the HDD with an SSD, because its faster and quieter.

Thermals are excellently managed. During a combined CPU + GPU stress test:
Max CPU temp = 75 degrees Celsius
Max GPU temp = 70 degrees Celsius

It's a lot faster now, but it's still really quiet and power efficient, so it still serves its purposes as a quiet media playing machine.
Very happy with the upgrade.