What does it even do, is my question. I see the option all the time but really have no idea what it does. I've checked it, I've un-checked it, and notice no difference. Both in WoW as well as other games. Granted, I didn't do much of an in-depth experiment and all that jazz. Still. What it do?
^ You can't un-read it. <Obvious Troll> is Obvious! - Gamefaqs Troll Raid 2010 - Trollinomics
With it on, games lock at a smooth 60 fps (box checked) with no screen tearing in big action games like shooters
With it off, games run to their full extent and take advantage of your GPU, reaching exceptional frames per second, and not keeping up with your screen's refresh rate, the visuals "rip" when spinning very fast
It annoys some people and others just like to brag about playing at 200fps
Some, play at a stable 60fps, not a HUGE difference in my own opinion.
Vsync= Vertical Sync
P.S. I play with it on because I like how it looks and I just don't see the difference in super high fps
AMD Phenom II X4 965 OC@3.9Ghz/6Gb DDR3 G-Skill RAM/HIS Radeon HD 5770 IceQ 5/SATA III 1TB 7200 RPM HD/Antec 750w PSU/Antec 902 Case/ASUS M4A89TD-USB 3.0
Google it. I'm so tired right now that all I'm going to do is quickly describe it.
It renders and displays a new image faster than your monitor can display it. Most monitors are at 60hz, so they can't display anything higher than 60FPS, or 60 individual, different frames every second.
If you're hitting over 60 FPS, you may start to see the top half of your screen not matching with the bottom. It starts to show one frame, then shows another before the first is done, and the result looks weird.