all depends on what gfx card you use(would have to be a high end Nvidia 950GTX and above with 2GB/4GB), whether you stream with x264 or NVENC, also on the OS & amount of Ram in the system, anywhere between 8 - 32GB Ram I think is good. And of course, it all depends on your internet speed - the upload mostly, not the download, you might find basic upload, 2mb/s, might not be good as you would have to lower the bitrate considerably, making the stream pixelated. So you may need a bigger upload in your internet setup, 5mb/s+, to be safe. with 5mb/s+, it is possible to stream with NVENC, with a decent bitrate of about 2.5mb/s, using your gfx card to encode the stream, that will lower CPU usage, as using x264 encoding uses up CPU.
