If you are using a secondary streaming computer you have a few possibilities:
1. Capture card on the streaming comp.
This means you have to buy a capture card that will go to a free PCIe slot.
You'll use no resources on the gaming PC, OBS will run on secondary PC.
2. Using the NDI plugin on both PCs.
No additional purchases are required if your router is good enough.
The NDI plugin will pass an uncompressed RGB stream to the secondary PC, requiring 200~ish Mbps of uncongested internal network bandwidth. The gaming PC will experience the performance penalty from the OBS's capture method (DXGI) and some additional CPU load from the handling of the uncompressed stream (for my 6700K that was <10% extra load). The encoding will happen on the secondary PC.
3. Using the RMTP + nginx/VLC method.
I have not personally used this but afaik you'll be partially encoding the stream on the gaming PC and then re-encoding it on the second PC. You'll need some internal network bandwidth but the amount depends on the internal streaming settings - nevertheless, it is less network intensive than the NDI plugin method. It works by sending the stream over internal network and translating it to video via a solution of your choice (VLC or such) on the secondary PC and then recapturing that in the OBS.
The penalties are otherwise identical to method 2, except there there is usually a light encoding on the gaming PC and then an additional DXGI capture on the secondary PC.
Irregardless of which streaming method you choose, it comes with a few caveats; if you want/need to use any filters separately on different parts of the stream scene (for example the webcam needs green screen to be keyed out, contrast or gamma needs to be adjusted etc.) you'll need to do that on the first PC or they need to be plugged in to the secondary PC.
Also, you'll need to manage two PCs, which might make it easier to separate the streaming from the actual gaming or make the whole thing a pain in the ass. Your mileage will vary.
Also, none of these solutions demand you to use CPU nor GPU encoding, per say. It will be your choice. The CPU encoding method (x264) will be higher quality per outbound bitrate than the NVidia's proprietary, accelerated method (NVENC), although they both output H.264. (I dare to claim you'll achieve the same quality with NVENC than the with the x264 by using 30-40% higher bitrate, depending on your other settings.)