[Guide] Tweaking the setting to get less input lag in games

Couple of days ago I came across a thread in OCN (click here to check it out) that talked about the things you could do to lower the input lag of your PC. Why should you care? Because less input lag translates to a smoother gaming experience. You might be getting 120FPS or more, but it still could feel choppy if you have a high input lag.

While I have a decent PC with me (right?), I have been having similar issues with Crysis 3 multiplayer (click here to go to my Crysis 3 game play videos on YouTube), which is pretty much the only game that I play regularly. It didn’t feel smooth at all. I had some hard time aiming and it drove me insane. This happened even with a reasonably high refresh rate of 96Hz. It seemed weird why I would get a lag at such a refresh rate even when the frame rate wasn't dipping below the refresh rate. Naturally, I blamed the wireless mouse at first. But it seemed that I had been having some DPC latency issues. And some of the things this guy mentioned, helped me to dramatically improve responsiveness in Crysis 3, even with massive ping times.

Few of the things that the guy suggested can be considered hardcore. Things such as uninstalling the Keyboard/Mouse software is a big no no. I need the ability to remap the keys of the mouse and the keyboard in difference apps. Further, disabling the virus guard and Anti-Spyware software is not a wise thing to do.

I performed a lot of changes in the UEFI that he suggested. The biggest change to the DPC Latency was caused by disabling HPET (High Precision Event Timer). But I kept the USB 3.0 settings in tact. Besides, I had disabled a lot of things that I didn’t use anyways.

He also suggested disabling all the power saving features of the CPU. Some people do that when they overclock the CPU but I have never turned off the power saving options with any of the CPUs. Besides,  it is impossible for the CPU to be in a low power state when you are inside a game. But the clock rate fluctuations might cause stuttering, so I just disabled it. But I wanted to see how much power the CPU will use if I disabled all the power saving features (that is the C states) and it amounted to like 25W when I checked it through AISuite. Usually when all the power saving features are ON, it could even go down to 1W. This didn't change regardless of whether I had dynamic clock scaling (turbo boost) enabled or disabled or whether I had EIST enabled or disabled. So I disabled both so that the clock speed doesn't fluctuate. I further set the power settings to "High Performance" in Windows Power Management section. However, since C states are still enabled, there is a small lag when the CPU comes from a power saving state to the fully operational state. But like I said, this should not cause any issues once you get inside a game.

Windows 8 and DPC Latency

If you measure the DPC Latency using LatencyMon, Windows 8 has a very high DPC (Deferred Procedure Call ) latency. In Windows 7, the same PC would have had about 100us of DPC Latency. Is this a problem?

If you do not know what DPC latency is, read the part: "Background information: Why drop-outs occur", at the bottom of this link.

Basically, what it says is that if the DPC latency is high, you will get pauses in real-time operations, such as listening to music and playing a video. Lower the DPC latency, the better. Most of the time, a high DPC latency is caused by bad drivers which spend too much time in the DPC routines. The drivers have to wait for their DPC routine until the one before them finishes with its DPC routine. When these waits become too long, you will get pauses or drop-outs in real-time operations.