Is it better to upgrade my PC or build a new one?

If you're willing to spend around $2000, I'd just say go for a full build. You can get a great streaming setup for Fortnite for way less than that. Also, consider getting an NVIDIA GPU since it allows you to use NVENC in OBS for better performance while streaming.

At this price point, upgrading might be tempting, but you'll probably want to build new soon anyway. Consider something like the 5070 Ti for a good balance between price and performance, and keep in mind that new-gen parts usually yield better gaming performance!

Upgrading doesn't seem feasible here since you'll end up needing to swap almost everything anyway. With your budget, you're at a good point to consider either a prebuilt or a custom build. Prebuilts come with warranties and take the hassle out of troubleshooting if something goes wrong. On the other hand, building it yourself can save you some cash and let you pick your parts. Just make sure your RAM is fast enough and go for dual stick setup if possible!

Honestly, I wouldn't bother upgrading. Once you start replacing one part, you'll likely need to change others too, which can turn into a whole chain reaction. With a $2k budget, you could easily build a solid setup for 1080p gaming—probably even overkill for what you need, but it'll last you a while!

I actually put together a build list recently. You could check out something like this: [build link]. It gives you room for a Windows license and an extra SSD for games. If you're considering upgrades instead, secondhand parts could save you money. Just remember, you’ll need to budget for a new PSU too.