Why do we need refresh rates at all?

[Chief Blur Buster]

If this is what G-SYNC and FreeSync are doing, then color me impressed. Clearly I need to give these technologies a 2nd look.

I am very impressed at what GSYNC does. However, GSYNC doesn't provide CRT motion clarity. It's important to understand what it is doing, however. I have quoted a section from my GSYNC Preview #1 and also GSYNC Preview #2:

G-SYNC: Eliminates stutters, tearing and reduces lag, but not motion blur.
Strobing: Eliminates motion blur, but not stutters or tearing.

Motion blur eliminating strobe backlights (LightBoost or ULMB) always looks best when strobe rate matches frame rate. Such strobe backlights tend to run at high refresh rates only, in order to avoid flicker (to avoid eyestrain-inducing 60Hz style CRT flicker).

We found that G-SYNC looked nicer at the low frame rates experienced in both Battlefield 4 and Crysis 3, while ULMB looked very nice during Counter Strike: GO. We did not yet do extensive tests on input lag, but preliminary checks shows that ULMB adds only approximately 4ms (center/average) input lag compared to VSYNC OFF or good frame-capped G-SYNC. If you do, however, use ULMB, and you prefer not to fully lock the frame rate to refresh rate, then using a close frame rate works well (e.g. fps_max 118) as a latency compromise, if you prefer the motion clarity of ULMB.

It is a personal preference whether to use G-SYNC or ULMB. As a rule of thumb:

G-SYNC: Enhances motion quality of lower & stuttery frame rates.
Strobing: Enhances motion quality of higher & consistent frame rates.

[RealNC]

Chief, the question was about fixed refresh rates and why we need them. G-Sync fixes *exactly* that.

Motion blur was not part of that question at all

[Chief Blur Buster]

Chief, the question was about fixed refresh rates and why we need them. G-Sync fixes *exactly* that.
Motion blur was not part of that question at all

Ignoring motion blur, you're right.
The OP's talk of CRTs (renowed for motion clarity) threw me off the trail somewhat.

Why must a GPU be talking to a LCD monitor at some predetermined frequency? Couldn't the GPU just send a new frame to the monitor "when it's ready" and get us a perfect tear-free low-lag image every time? I'm sortof baffled this hasn't happened yet. Comments?

It's happening already: RealNC is correct, this is eaxctly what GSYNC is doing.

[Alcazar]

Tremendous amounts of useful information here, thanks.

I heard from my friend at nvidia that G-SYNC is only capable of 8bit color right now, did you guys know that? I'm sure the nvidia boys will get that resolved though. Same with higher resolutions like 2560 and 4K, eventually.

So now I'm wondering if we could expect a DP1.2a connected 4K display to give us >60hz at *lower resolutions*. My 32" Dell 4K is pretty stupid right now and won't even drop to lower resolutions unless you manually turn off DP 1.2. I imagine future 4K panels will be smarter and allow >60hz via GSYNC at "gaming resolutions" while still allowing us to have 4K for 2D workspaces. Not to mention 10bit color.

But this is exciting times indeed, and long overdue!

[RealNC]

(The discussion about color banding was getting a bit off-topic, so that part was moved to its own thread: http://forums.blurbusters.com/viewtopic.php?f=7&t=927)