it would look strange if I had a better gaming machine than my Son
What if you get him a better gaming PC and take his machine for yourself? Isn't it an option?
Anyway, going for any mid-range CPU (Ryzen 5700/7600; i7-12700/i5-13400) will allow you for great speeds at negligible amounts of heat (especially if you undervolt them using your BIOS, not a difficult task) and for 32 or even more gigs of RAM (dunno about ECC though, don't see why you
actually need it but I'm open for your opinion).
As you're not a huge fan of gaming you can skip the GPU buying part and stick with your GT 1030 till it finally stops meeting your needs or melts due to ageing.
SSD-wise, just buy something NVME of a proper volume. You can use your old SATA one since it's fully compatible with any modern motherboard.
PSU... getting the best 500 W unit on the market is probably an overkill but you never know.
Wi-Fi is now often included onto motherboards.
The Matrexx 55 Mesh case is more than capable of big fans and low temperatures. Don't buy the vanilla Matrexx 55, it's got broken SATA SSD mounts. Yeah, it's got a window but you can limo that window out...
NB: in case of going for LGA1700 you should take in consideration their rectangular shaped CPUs might have bad contact with socket pins resulting in overheat and/or incorrect work. Either it's unacceptable for you and you stick to AMD (Intel's 11th gen and older tech sucks balls in terms of efficiency compared to Ryzen 5000/7000 Series and newer Intel CPUs) or consider buying an alternative socket bracket (must be sold for $10 or less, easy to install, doesn't break warranty).
NB2: AMD CPUs are desperate for coolers without direct pipes contact. Box cooler must be fine considering the fact you can limit your CPU's wattage as you like.
NB3: every modern GPU can be underclocked and/or undervolted so it will perform cooler and (sometimes) slower. Just avoid RTX 4060 series, their price is complete nonsense.
And yeah, RGB can be turned off on most parts. Just avoid
FRGB variants.