Please help me to buy the right PC for my OBS needs

[Barabba]

Hi, I need to buy a PC which can show me on a 4K TV a mosaic of 9 cameras, made by OBS. 7 cameras have a main stream 1080p h.265+ and substream 640x360 also on h.265, the last 2 ones has the man stream 4M 1440p.

I'm looking for a motherboard+processor+graphc card able to do the job, nothing else is requited, I would focus on a graphic card that may help the CPU for decode, reducing the power dissipation, enloging the life. My question are:
1) Which video card (with reasonable price) can decode 9 streams as described above? Since I have a 4K TV I may think to decode the main stream, but if I'm asking too much I can adapt to substream.
2) Does OBS use video card to decode those streams and free then the CPU?
3) the two 4mpx cameras are chosen to crop and diplay a reduced area, is OBS able to ask video card to decode and ten crop to screen that uncompressed part of video?

Which components are you suggestiong me? For example, a Core i7-7700, RAM 32GB, and NVIDIA GeForce GTX 1660 SUPER can be enough for that?
Thank you!

 

[Barabba]

According to what I'm reading around, a GTX 1660 SUPER should handle all thr 9 streams, but does OBS use this decode function of the graphic card?
What about a GTX1050Ti? I can save some money. I just need to decode, no transcode..

 

[AaronD]

I just need to decode, no transcode..

Video formats are designed to be cheap and easy to decode, at the expense of encoding. It's most of why encoding takes so much effort: the irreducible complexity of getting video through a small channel (consumer internet) is pushed hard to that side of things.

So you could probably receive all 9 of your incoming streams on a 10-year-old basic laptop (basic even when it was new), with no GPU at all.

In other words, if OBS runs at all, then it'll probably do that too.

 

[Lawrence_SoCal]

Depending on your location, a 1050Ti and a 1660Super may not have much price difference. But with the 1660Super using a new gen chip, and even that being multiple generations old at this point, the small price premium for the 1660 Super would be my starting position (though at this point, I'd more seriously consider an RTX2060 or similar for better longevity/support ... hopefully).

why would i7-7700 be so much cheaper than later generations? Win11 support... End-of-Life on Windows for older CPU/PCs
- an i7-7700 falls off Windows OS support (Win10 this Oct. )... i think (up to you to confirm). If trying to make what you already have work, then sure... but if Internet connected, one should ONLY be using a regularly patched Operating System... so make sure to get a Win11 supported PC (even if I haven't migrated, and am waiting as long as I can). Or migrate older hardware to Linux [and that learning curve, if not already proficient].

Also, consider your output, and how long you want that for? ie H.264, H.265, or AV1... each take a WHOLE lot more processing to encode... with only latest GPUs supporting first-gen consumer hardware AV1 encoding... but if you want something that will last years, you will probably want to migrate to AV1 at some point in coming years (if not already with YouTube) .. .depends