Sensor and Performance

The ASUS ROG Keris is equipped with the PixArt PMW3389. According to specifications, the 3389 is capable of up to 16,000 CPI, as well as a maximum tracking speed of 400 IPS, which equals 10.16 m/s. Out of the box, four pre-defined CPI steps are available: 400, 800, 1600, and 3200 CPI.

All testing was done on the latest firmware (1.00.09). As such, results obtained on earlier firmware versions may differ from those presented hereafter.

CPI Accuracy

"CPI" (short for counts per inch) describes the number of counts registered by the mouse if it is moved exactly an inch. There are several factors (firmware, mounting height of the sensor not meeting specifications, mouse feet thickness, mousing surface, among others) which may contribute to nominal CPI not matching actual CPI. It is impossible to always achieve a perfect match, but ideally, nominal and actual CPI should differ as little as possible. In this test, I'm determining whether this is the case or not. However, please keep in mind that said variance will still differ from unit to unit, so your mileage may vary.


I've restricted my testing to the four most common CPI steps, which are 400, 800, 1600, and 3200. As you can see, deviation is exclusively positive and decently low, which is a good result. In order to account for the measured deviation, adjusted steps of 400, 800, 1600, and 3100 CPI have been used for testing. Curiously, despite the 3389 allowing for adjustments in increments of 50 CPI, the software doesn't.

Motion Delay

"Motion delay" encompasses all kinds of sensor lag. Any further sources of input delay will not be recorded in this test. The main thing I'll be looking for in this test is sensor smoothing, which describes an averaging of motion data across several capture frames in order to reduce jitter at higher CPI values, increasing motion delay along with it. The goal here is to have as little smoothing as possible. As there is no way to accurately measure motion delay absolutely, this can only be done by comparison with a control subject that has been determined to have the lowest possible motion delay. In this case, the control subject is a G403, whose 3366 has no visible smoothing across the entire CPI range. Note that the G403 is moved first and thus receives a slight head start.


First, I'm looking at two xCounts plots—generated at 1600 and 16,000 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." As you can see, such a kink is visible in the 16,000 CPI plot, although just barely, which suggests there is smoothing present. We can also see fairly low SPI timing jitter.


In order to determine motion delay, I'm looking at xSum plots generated at 1600, 5000, and 16,000 CPI. The line further to the left denotes the sensor with less motion delay. 1600 CPI shows no motion delay differential. This is true up until 4900 CPI. At and above 5000 CPI, a motion delay differential of roughly 16 ms is present, all the way up to 16,000 CPI. This is unlike any 3389 implementation I've encountered so far. Typically, smoothing kicks in as early as 1900 CPI on the 3389, so the way it is done on the Keris is indeed preferable.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or short SRAV). It's not about the mouse having a set amount of inherent positive or negative acceleration, but about the cursor not traveling the same distance if the mouse is moved the same physical distance at different speeds. The easiest way to test this is by comparison with a control subject that is known to have very low SRAV, which in this case is the G403. As you can see from the plot, no displacement between the two cursor paths can be observed, which confirms that SRAV is very low.

Perfect Control Speed

Perfect Control Speed (or PCS for short) is the maximum speed up to which the mouse and its sensor can be moved without the sensor malfunctioning in any way. I've only managed to hit a measly 4.5 m/s (which is within the proclaimed PCS range), at which no sign of the sensor malfunctioning can be observed.

Polling Rate Stability

Aside from the odd outlier at 125 Hz, all available polling rates (125, 250, 500, and 1000 Hz) look and perform just fine. Polling stability is unaffected by any RGB lighting setting.

Paint Test

This test is used to indicate any potential issues with angle snapping (non-native straightening of linear motion) and jitter, along with any sensor lens rattle. As you can see, no issues with angle snapping can be observed. No jitter is visible at 1600 CPI. 4900 CPI is the highest CPI step without any smoothing and shows minor jitter. At 5000 CPI, smoothing is first applied, resulting in a jitter-free display. 16,000 CPI has the same amount of smoothing applied, but shows major jitter regardless. Lastly, there is no sensor lens movement.

Lift-off Distance

The Keris offers multiple ways of adjusting LOD: several pre-calibrated surface options, two pre-defined LOD levels (high/low), and manual calibration. Through a recent update, ASUS has disentangled these options a bit. By default, the "no calibration" preset is active, which has the sensor not track at a height of 1 DVD (<1.2 mm) if set to "low." If set to "high," the sensor will track at a height of 1 DVD, but only intermittently at a height of 2 DVDs (1.2 mm<x<2.4 mm, x being LOD height). Furthermore, several pre-calibrated surfaces are available to choose from, which can then be fine-tuned manually by adjusting the high/low selection. Some caution is advised when selecting the Balteus and Balteus Qi surfaces set to "low," as these will result in the sensor no longer tracking on a regular cloth pad. ASUS is currently looking into solutions to provide users a recovery option. Lastly, performing a manual calibration may lower LOD beyond the default. In my case, doing so resulted in an LOD below 1 DVD. Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

Since mechanical switches are being used for the buttons in most computer mice, debouncing is required in order to avoid unintended double clicks. Debouncing typically adds a delay (along with any potential processing delay), which shall be referred to as click latency. As there is no way to measure said delay directly, it has to be done by comparing it to a control subject, which in this case is the Logitech G203. Click latency has been measured to be roughly -0.9 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. Please keep in mind that the measured value is not the absolute click latency. Comparison data comes from this thread as well as my own testing, using qsxcv's program.