Few things about Quick-Sync. It's been out there as an encoder for quite a while now as well as in OBS. Quick-Sync is available on any intel i-series 2***/3***/4*** unless you are using a p-series motherboard (not avaiable for them). Encoding on cpu wins easily when comparing image quality(for now). If you don't have a good internet, then don't even bother trying to use quick-sync as the image quality on stream will be heavy based on your upload speed.

To comment on this, I tried Quick Sync awhile ago, and while trying to stream at a 2000kbps bitrate at 45fps, I got reports that my stream was incredibly pixelated and almost unwatchable. I think that if you're a Twitch partner and always will have transcoding options, Quick Sync might be a viable alternative assuming you have the internet to support it.

However, if you're trying to stream and you're not partnered, I wouldn't recommend Quick Sync; because either you don't have the internet to support it, thus giving you a worse-looking stream, or your potential viewers won't be able to watch you because your bitrate will have to be much higher than it was previously to make up for the hurt in quality. This raises the bar in terms of internet speed that your viewers must have in order to be able to watch the stream without lagging/buffering. Sure you'll get better in-game performance, but if your stream is going to be unwatchable/incredibly low quality, then why stream?

Since OBS added "preset" options to quick-sync it has been better now. So now a 540p/616p stream at 30, maybe 45 fps with bitrate of around 2000-2500 would look just fine and watchable.
Best way is to try it out yourself and see if it is worth it.

Oh, I didn't know this. I'll have to experiment around a bit more with it then. It's been awhile (1-2 months) since I've played around with it, so I might consider trying it again if the picture quality isn't too poor compared to x264.

Thanks for the info!

improvements have been made to quick sync but is still not as good as CPU x264 encoding. If you don't need the performance boost (chances are you don't if you're using a CPU that supports quick sync - but you might), you should probably stick to using the CPU.

In order to use quick-sync, your intel gpu have to be in use. First it needs to be enabled in bios, also it needs drivers and for the usage part, easiest way is to fake another monitor. If you have 2 monitors then select your other one to use intel hd graphics. On win8 igpu doesn't have to be in use in order to use it with OBS.

In fps games even if quick-sync doesn't provide the same image quality on stream, it's still a good option to have because you don't get any input lag, fps decrease or anything that a regular cpu streaming could give. So streaming a lower quality stream while being able to play as usual could be one of things a lot of players would go for imo

in my experience, input lag is dependent on capture method rather than encoding method. I had input lag when i used screen/window capture, but once I switched to game capture that went away. Of course, lower fps results in an increase in input lag, but its negligible if your fps is well into the hundreds. fps drops aren't an issue for me when streaming but I do have an i5 4670k so there are plenty of lower end/older CPUs that support quick sync. i'm no expert so YMMV, but unless you have significant fps issues when streaming, you don't need to use quick sync.

if you do have fps issues, quick sync is definitely worth a shot.