Sensor and Performance

The Model O- is equipped with the PixArt PMW3360. According to specifications, the 3360 is capable of up to 12,000 CPI, as well as a maximum tracking speed of 250 IPS, which equals 6.35 m/s. Out of the box, there are four pre-defined CPI steps available: 400, 800, 1600, and 3200 CPI.

CPI Accuracy

"CPI" (short for counts per inch) describes the amount of counts registered by the mouse if it is moved exactly one 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 vary 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, there is no deviation at all, which is an outstanding result.

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, it 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.


First, I'm looking at two xCounts plots to quickly gauge whether there is any smoothing present, which would be indicated by any visible "kinks." Typically, the 3200 CPI plot would be expected to show such "kinks" given the 3360 usually has 32 frames of smoothing at and above 2100 CPI, which amounts to an added motion delay of roughly 4 ms at the lowest possible speed. As you can see, this is the case here, which confirms that the 3360 in the Model O- indeed performs as expected. As an aside, it's positively remarkable how tight the grouping is, which indicates that the SPI timing has little jitter.


In order to verify the results from the xCount plots above, I'm looking at xSum plots generated at 400, 1600, and 3200 CPI. The line further to the left denotes the sensor with less motion delay. At 400 CPI and 1600 CPI, motion delay is identical; at 3200 CPI, motion delay is roughly 4 ms. All of this is expected behavior and merely confirms the results seen above.

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 speed no sign of the sensor malfunctioning can be observed.

Polling Rate Stability

All four possible settings (125 Hz, 250 Hz, 500 Hz, and 1000 Hz) look nice and stable.

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. There is no jitter visible at 400 and 1600 CPI, but some jitter is observed at 12,000, which is to be expected. Furthermore, no sensor lens rattle is present.

Lift-off Distance

The Model O- offers two pre-defined LOD levels to choose from. On the 2 mm setting, the sensor does not track at a height of 1 DVD. On the 3 mm setting, the sensor tracks at a height of 1 DVD, but not at a height of 2 DVDs. It should be kept in mind, however, 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 G100s. Click latency has been measured to be roughly +3.8 ms at the lowest debounce time setting (4 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.