I moved away from the mini-tower or tower PC paradigm several years ago and now just buy middle to low tier mini PCs. IMHO PCs have become consumables, that is to say you expect to get a good 5-7 years out of them and by that time they are not all that useful compared to a new unit and the same cost will get you N times more computing power after 5 or more years have passed. Computing hardware is just too integrated and complicated to fix when something finally goes wrong, as you are now learning. For around Euro 500 (for the PC itself) you can get a good value, middle tier processor plus a decent amount of memory and storage. AMD's Ryzen family seem to be providing the best performance to cost ratio these days.
Examples:
https://www.amazon.de/MINIS-FORUM-UM870-Slim-Mini-Computer/dp/B0DLB8FMX7
https://www.amazon.de/-/en/Beelink-EQR6-6900HX-PCIe4-0-Computer/dp/B0CY2C4K2W
Both of these are reputable companies, not a generic, funny-name, Asian unknown. My main PC is a Minisforum HX90 that is now about 2 years old. Love it. It replaced a tower PC that ran an Intel i7-4770k, and the HX90 with a Ryzen 9 5900hx is 3 times faster, smaller, and quieter.
Examples:
https://www.amazon.de/MINIS-FORUM-UM870-Slim-Mini-Computer/dp/B0DLB8FMX7
https://www.amazon.de/-/en/Beelink-EQR6-6900HX-PCIe4-0-Computer/dp/B0CY2C4K2W
Both of these are reputable companies, not a generic, funny-name, Asian unknown. My main PC is a Minisforum HX90 that is now about 2 years old. Love it. It replaced a tower PC that ran an Intel i7-4770k, and the HX90 with a Ryzen 9 5900hx is 3 times faster, smaller, and quieter.