@SimsLover2247 First, I don't think that upgrading your existing computer is the way to go. An Nvidia 2070 would cost you around $500, but you'd also need a new power supply ($100); the stock model you currently have can't support a high-end GPU. Your processor is below the recommendations for both Conan Exiles and the newest Fallout; a new one would cost at least $300, depending on what you wanted, plus you'd need a new motherboard ($120 and up) and CPU cooler (maybe $80 for liquid cooling). Your RAM might not be compatible with the new board, and your case might not fit the parts. So you're better off starting over.
Edit: I just saw your edit, and I still think you'd end up needing more expensive upgrades before long. Plus, neither a 1050 ti nor a 580 would allow you to run your other games in ultra.
On that note, I found a few models that could work for you. A budget of $1000-2000 is a wide range, but I aimed for the lower end in the prebuilt models.
This one is the cheapest I'd go, and it would need a couple of improvements that would raise its initial price of $900. Its Nvidia 1070 ti would be fine for all your games for now, although that may not be true in the future; the 1070's benchmarks are weaker than the newer 2070's. It has a single 500 GB SSD, which would probably end up not being enough, but it would be easy to install a second hard drive when you needed it. (Maybe $50 for a quality HDD or $110 for an SSD.) It also has only 8 GB memory, but you could buy a second RAM stickfor maybe $60-70, depending on what comes already installed. (You'd need to match the existing one by serial number, but that shouldn't be too hard.) So if you're really into saving money, you could make this model into what you wanted with a bit more money.
https://www.newegg.com/p/N82E16883289015?Item=N82E16883289015
This one, at $1200, comes with a better processor, an Nvidia 2070, 16 GB of faster RAM, and a 1 TB SSD already installed. It wouldn't need any additional parts, if you'd rather not have to upgrade yourself.
https://www.newegg.com/p/N82E16883289031?Item=N82E16883289031
These are both good computers, but they have their disadvantages, especially for what you want to do. The best experience will come from playing off a solid state drive, which will be faster for most modern games, although TS4 wouldn't notice a difference, and 500 GB may not be enough. You may also want a liquid CPU cooler; I would expect that the above models only have air cooling. Furthermore, their power supplies are not the highest quality.
If you want all these upgrades, you're better off going with a custom build. I put together one on CyberpowerPC that would start at $1406, although you could add further upgrades. This model would have:
- an AMD Ryzen 2700X processor, almost equal to an Intel 9700K
- an Nvidia 2070, the cheapest version
- 16 GB RAM 3000 MHz, currently on sale
- a 1 TB Intel 660P NVMe SSD (SATAs are usually cheaper, but not with this offer)
- liquid cooling, an 80+ Gold power supply, and an MSI motherboard with room to add more parts
Additions you might want to consider:
- an Asus brand graphics card, for $65 extra, but only if you're planning on keeping this card for a while; if you want to upgrade in a couple of years, you can go with the cheaper option
- an Nvidia 2080 would cost $249 more, or $272 for the cheapest Asus
- a video capture card for streaming, starting at $164, although it would be cheaper to buy one on Amazon (same version is $120) and install it yourself
- a Corsair brand 750W Gold certified power supply, for $62, which is supposed to be good for up to 10 years
- a 240mm liquid cooler (starts at $20 more)
- a second 1 GB SSD, for $125
None of the above are strictly necessary; these are more ideas for you to think about, and what you want will depend on your plans for this computer. For example, how long do you want to keep it, and do you want to upgrade parts as you need them? And are you comfortable doing so? A bit more money now will make smaller, cheaper upgrades possible later, like swapping out the graphics card for a new one. These models in particular are meant to support multiple upgrades, and it would be fairly easy to handle this yourself.