by Ray Bryden on November 15th, 2009
In the past, when I configured my video each time I upgraded my system, I made sure to check-off the box for V-Sync under the graphics options because the resulting effect on the sim was quite smooth and produced the best moving image quality with little or no stutters or “artifacts”.
So I have been quite happy with this and what I would describe as intermediate settings (no shadows) on an intermediate quality video card and CPU/motherboard. But although the graphics quality is more than sufficient for my needs I have plateaued in my driving skills, which I always blame on lack of available time to devote to practice and improvement.
But after reading a couple of recent forum threads related to graphics settings (specifically V-sync) and input lag, I was curious if it would have any affect on my system and my limited control skills. The V-sync is a graphics setting which locks the graphics card into a pace which matches the refresh rate of the monitor, so the resulting stream of images progresses in a controlled pattern and the result is a quite smooth transition from frame to frame, which is pleasing to the eye. When the graphics are not V-sync’ed you can allow the graphics card to run unlimited, allowing it to generate as many frames as it can (but which are only displayed at the rate of the monitor refresh, so several frames are drawn by the card but not displayed), or you can cap the graphics card at a certain frames per second (fps) rate, defaulted at 83. Often, the result of capped or unlimited settings is a variable number of dropped frames, leaving the rate of change of the view to vary from frame to frame apparent to the viewer. As a result the scene flows in a much less smooth sequence and is generally less pleasing to the eye. Some even report eyestrain problems when running with V-sync off.
I decided to run a quick test to determine if V-sync settings played any role in my driving performance. When V-sync was on I noticed a barely perceptible lag between the time of my inputs (turning the wheel or applying pedals) and the resulting change in the inputs displayed on the screen. I figured the latency time was observable but not significant enough to play a role in my driving experience. So I took out the new Corvette C6.R – a car I am pretty unfamiliar with – to a test at Watkins Glen (Boot) – a track I am pretty unfamiliar with – and could only manage to set a time just under the 107% of the world record after about 12 laps with quite a few spins. Then I turned off the V-sync and limited the card to 83 fps, and noticed the lack of smoothness of the flow, but was able to mostly ignore it. I also noticed that the wheel appeared to have no noticeable lag between my inputs and the on-screen wheel response. I also found that my control was much better and though I was in hot-lap mode I made much fewer mistakes and got my personal best time down my almost a two and a half seconds (104.5% off the world record) on my eleventh lap. I repeated the test with V-sync on and spun quite a bit more and struggled to get within a second and a half of the V-sync off time after 12 laps. Scott Husted reported an almost identical experience in his tests with and without V-sync, and many others have confirmed the same thing.
This was quite an eye-opener for me. I didn’t think the lag was that bad to begin with, but once it was reduced I noticed that I had much better control over the car and was able to catch potential spins with much more ease and confidence compared to when V-sync was enabled. I am going to follow-up with a more fair and extensive test to try to better characterize the latency and attempt to quantify how my graphics settings affect it and whether it plays a role in the validity of my past performance excuses.
But in the end it comes down to driver preference and some cannot bear to shut off the V-sync setting due to the loss of smoothness. Some will not have any change in the input latency with changes of this nature as it is very system-specific. However, at this point I highly recommend trying to drive without it enabled to see if it improves your sense of control, whether or not you can notice the input lag.
My only trouble is I have to find some new excuses for being so far off the pace, because it surely can’t be due to my skills. Ahem.