G-Sync is an expensive technology, but that's because it uses a hardware solution to perform the communication between the GPU and display. FreeSync uses the V_BLANK attribute found in the VESA standard to activate its technology, making for a "free" firmware / scaler alternative that theoretically performs similarly. Neither approach to frame smoothing produces a noticeable impact to actual framerate output -- it's just changing the frequency at which frames are drawn to the display to better match the GPU's frame output.
We mentioned this in our coverage of the Omega driver updates, but FreeSync is expected within a few weeks and has picked up the support of nearly 95% of the panel suppliers. All AMD GPUs hosting the current gen display controller -- that'd be the 260, 265, 285, 290/290X, and 295X2 -- are capable of running displays with FreeSync. The 270 and 280 series cards are unsupported due to their utilization of the previous gen display controller, despite being current-gen architecture cards.
The demonstration showcased FreeSync vs. V-Sync vs. neither. FreeSync smoothed out the framerate to a similar effect as G-Sync, though we'd need to see the two side-by-side to truly tell if there are quality gains with either approach. It's an effective technology that eliminates tearing and stuttering, as advertised. Tearing occurs when V-Sync is disabled and the GPU delivers part of the next frame, creating a horizontal tear across textured elements and objects in the game (the previous frame and next frame are being shown simultaneously). Stuttering occurs when V-Sync is enabled, which eliminates tearing but results in frame skipping (redrawing the previous frame) when the GPU doesn't meet its deadline with the display.
By enabling either FreeSync or G-Sync, the display is conforming its refresh rate to match the frame output of the GPU, ensuring an almost entirely smooth gameplay experience. The objective of each technology is effectively identical, but the main difference is that G-Sync requires an expensive piece of hardware and FreeSync requires GCN + a supported panel and scaler. Neither is the perfect, all-compatible solution, but they're both a good start and visually effective.
- Steve "Lelldorianx" Burke.