Vsync in Games

[enaberif]

Currently playing Firefall and notice that when I have vsync enabled my FPS is always at 60 and my CPU usage is below 50%.

But I notice that when I disable vsync my FPS is 60+ but my CPU usage on core 1 jumps to 80-90%.

Why would disabling vsync cause high cpu usage?

[YukonTrooper]

Because your CPU is rendering more frames. Or rather, your GPU is rendering more frames and subsequently your CPU's workload increases.

[ilya]

Less frames rendered=less stuff for your CPU to do.

[SKYMTL]

IN a rendering scenario, the GPU asks for frames to be pre-fetched by the CPU. As such, when the framerates go higher, the load on the CPU naturally increases as the GPU calls for more frames.

This is also why our PCI-E 2.0 versus PCI-E 3.0 tests on the GTX 690 resulted in similar performance at higher resolutions but lower resolutions and detail settings ended up showing a difference.

[enaberif]

So technically on systems with a limited cpu disabling vsync could potentially give you a decrease in performance for the game.

[gingerbee]

thats the bottle neck if the cpu cant keep up with the data need to render for the gpu it's like the cooks not keeping up with the waiters

[enaberif]

I've always just left vsync enabled as I found no difference aside from cpu usage go higher.

[Bond007]

Vsync IMO is only useful to limit your FPS if your running a less demanding game. For example an older source game that you get 150+ FPS...you are not going to see any of that, so you enable vsync that caps FPS at 60. It will lower GPU and CPU workload and therefore temps and power consumption (the last one maybe to a much lesser extent...not really sure). If you aren't ALWAYS over 60 fps, then disable it. If you leave it on and go below 60fps then it will cap you at 30 fps in my experience.

[jibz]

I alway use vsync as my rig is a monster and unleashing it results in huge power draw and heat output.

[On2wheels]

The 301 nvidia drivers have the adaptive vsync feature now.