Sensor and Performance

The Endgame Gear XM1 RGB 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.

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 actual CPI not matching nominal 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 as well.


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 a perfect 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—generated at 1600 and 3200 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." Typically, the 3200 CPI plot would be expected to show such "kinks" given the 3389 usually has 32 frames of smoothing at and above 1900 CPI, which amounts to an added motion delay of roughly 4 ms at the lowest possible speed. As you can see, this is not the case here, which is due to the XM1 RGB not having smoothing enabled, unlike most 3389-equipped mice. But there are kinks on display, you say? Well, yes, but they're not due to smoothing. Instead, these outliers occur with RGB lighting enabled. As soon as I turn off RGB lighting altogether, the plots look like this:


In short, tracking quality takes a hit as soon as RGB is enabled. Without RGB, tracking is near-perfect, with only very minor SPI timing jitter to speak of.


In order to verify the results from the xCount plots above, I'm looking at xSum plots generated at 1600, 3200, and 16,000 CPI. The line further to the left denotes the sensor with less motion delay. All CPI steps show no motion delay differential beyond margin of error. This is expected behavior and merely confirms the results seen in the xCount test above.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or SRAV for short). 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

Polling rate behavior is rather weird. 250 Hz shows no issues. Both 500 and 1000 Hz do show outliers, which, as seen in the last plot, are lessened when RGB lighting is disabled. Generally, the "Color Flow" lighting effect has worse polling stability than the other ones as well. Note that these polling outliers do not correspond to the outliers seen in the xCount plots above—as long as RGB is disabled, xCount plots look immaculate irrespective of visible outliers in Frequency or Interval plots. Although the polling instability is not a grave issue, Endgame Gear plans to address it in a thorough firmware update in the near future—no ETA has been given.

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. Jitter is under control all the way up to 3200 CPI. At 16,000 CPI, jitter levels go through the roof (beyond the stratosphere), however. This is expected due to the lack of smoothing. Lastly, there is no sensor lens rattle.

Lift-off Distance

The XM1 RGB 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 (<1.2 mm). On the 3 mm setting, the sensor tracks at a height of 1 DVD, but only barely tracks at a height of 2 DVDs (1.2 mm<x<2.4 mm). Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

While the XM1 RGB does use mechanical switches for its buttons like most mice, it does not debounce them in the traditional way. Instead, Endgame Gear uses something called "Analog Switch Technology," which basically eliminates all delay that would be introduced by traditional debouncing (using what essentially is a low-pass filter), while eliminating the possibility of double-clicking due to debounce values that are too low. For further details on this analog switch technology, please refer to the patent here. The absence of traditional debouncing also means I cannot use my usual method for determining click latency. As such, the less reliable and rather crude bump test will have to suffice. Using the bump test, my measurements suggest a click latency at least equal to or lower than the SteelSeries Ikari, which is considered as the baseline with 0 ms.