Advice Needed Need suggestions for building a streaming PC (Budget friendly, but i'm not poor lol)

So, basically, I've been getting into streaming and stuff, as my YouTube Channel passed 15,000 subscribers and I've been wanting to start Twitch.
I have a really good gaming PC, that I can play any games on... however I always seem to get extremely low FPS in OBS, Xsplit, and Bandicam when recording or streaming... and it breaks my head because I have an i7-6700K OC that is not even close to maxing out and my 1080 Ti is also close to maxing out but it's not... I've tried reinstalling Windows, and that didn't help, and I've tried lowering settings ingame and stuff and nothing ever works.
I play games at 1440p, 144fps and I realize that that causes some issues. Even when lowering graphics to 1080p 60, it's still dropping far lower in OBS than ingame... Like I can play games at a perfect 60 FPS and get only 5-10 in OBS or things alike...
So I've finally given up and want to invest in a streaming PC, as it can also double as a render node for 3D animations and other things.

I have a spare 970 lying around somewhere, and I think it'd be possible to use that to encode a 1440p 60fps stream from an Elgato 4K60 (as it can handle 1440p at 144fps -- what I play games at)...
I'll be using that as an input, but I need some kind of setup for the rest of the PC that'd be able to handle such a high bandwidth video load... It'll compress it down to around 15,000-25,000 kbps, so it's not going to be too bad...

Are there any specific CPU/Motherboard/RAM configurations I should go with, or would a normal i5 and like 16GB ram do it justice (remember, I'll be using it for 3D rendering as well... so it can't be too trash lmao)

Any and all suggestions are appreciated

I am not good at that stuff but good to know that you've crossed 15k subscribers thats a milestone, whats your channel name? and I would suggest to look on youtube for it, they are many channels that make custom PC for gaming/streaming.

I would look into those new i9s that are coming out then buy a graphics card when its top of the line instead of settling for any i7. i9 will eventually become the standard top shelf PC build, imo.