Sensor and Performance

The Dream Machines DM6 Holey S 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, six pre-defined CPI steps are available: 400, 800, 1600, 3200, 4800, and 6400.

All testing was done on the latest firmware. 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 consistently positive and consistently large. A subpar result overall. In order to account for the measured deviation, adjusted and mostly accurate steps of 400, 750, 1500, and 3050 CPI have been used.

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.


Usually, looking at an xCounts plot would allow me to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." Doing so here is impossible, however, as the DM6 Holey S cannot hold a steady polling rate of 1000 Hz. As such, I had to switch to 500 Hz to get any mileage out of these plots:


As you can see, the second plot does show a kink, although it's difficult to make out. This is in line with what to expect from a 3389, which typically has 32 frames of smoothing at and above 1900 CPI that is then doubled at 6000 CPI and 11300 CPI, respectively.


In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 3200 CPI. The line further to the left denotes the sensor with less motion delay. I can measure a minor delay of roughly 1 ms across the entire CPI range. I strongly suspect that this is due to 1000 Hz polling rate frequently dropping down to 500 Hz. Results at 500 Hz being very similar confirm this assumption. Steps at and above 1900 CPI show the usual 32 frames of smoothing, which results in an approximate motion delay of roughly 4.5 ms at lower speeds.

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

Whereas 1000 Hz is highly unstable and periodically drops to 500 Hz, both 125 Hz and 500 Hz are perfectly fine. Polling stability is unaffected by any RGB 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. Neither 1600 nor 3200 CPI show any noticeable jitter. Despite the significant amount of smoothing applied at that step, 16,000 CPI shows high but not excessive jitter. Lastly, minor sensor lens rattle can be observed.

Lift-off Distance

The DM6 Holey S offers three pre-defined LOD levels to choose from. At the default as well as the "L" setting, the sensor just barely (intermittently) tracks at a height of 1 DVD (<1.2 mm). This is still the case when using the "M" or "L" setting, albeit tracking is less sporadic. In short, the different LOD levels seem to barely change anything, if at all. 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 G100s. Click latency has been measured to be roughly +4.2 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. Note that testing was performed at 500 Hz in order to achieve more consistent results. 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.