9th Generation Intel Core i7-9750H (6-Core, 12MB Cache, up to 4.5Ghz w/Turbo Boost)
M.2 1TB PCIe Class 40 Solid State Drive
NVIDIA GeForce GTX 1660 Ti 6GB GDDR6
16GB, 2x8GB, DDR4, 2666MHz
Mine has a 5th Generation i7-5930K (6-cores, 3.5GHz, up to 4GHz on turbo), with 16GB DDR-4 RAM. Your processor is 4 generations newer than mine, and can clock 0.5GHz faster, but this old Haswell-E still runs any 3D application with ease. Of course, being a full-featured i7 helps, coupled with a modern RTX card - it can handle anything. Maybe the overpowered RTX 3090 makes up for the old processor. Sometimes I think I don't have enough RAM with 16GB, but that's easy to fix. 3D in general is a memory hog, so it helps to have more RAM. In this aspect, the days of 4GB and 8GB are gone. I believe 16GB is a minimum for handling 3D scenes nowadays.
The two things that will make the most difference for the type of work most of us do is RAM and graphics card.
Having the above said, I have to agree with @parkdalegardener. I have an old processor, but that doesn't seem to matter much. RAM and GPU seem to affect 3D performance more.
I've never ever done that, buy parts and build them in myself. I wouldn't know where to start.
I've always bought a PC in a store or someone build it for me. I am pre-computer era you know and everything I know so far is self taught. So buying parts and building them into a PC would be the next step for me.
I used to buy ready-made PCs, but over time I understood I was overpaying, and never getting exactly what I wanted. Even when the general specs matched, I was still not getting the make and model I wanted in that price range. I am specially picky on displays, mice, and keyboard, which are the things we will handle the most. When we buy ready-made, it's 1-fits-all.
In addition, my PC has no decorative lights or a transparent side to show them off. Nowadays people are paying for a computer mounted on a Christmas tree - and you bet that adds to the cost with no added benefit. I'd rather spend my money on a good CPU cooler to keep it stable, a case with good airflow and cable management, and an 80-Plus Gold Certified PSU that will hold everything stable in the long run. I choose parts that will last from makers I trust - that is an investment in the future. These machines will last for at least 6-8 years.
It ends up cheaper than a ready-made PC, mostly because it only has what I need. Perhaps the only bummer is that I have to buy a Windows license on top of it.