Sensor and Performance

The Endgame Gear XM2w 4K is equipped with the PixArt PAW3395. According to specifications, the 3395 is capable of up to 26,000 CPI, as well as a maximum tracking speed of 650 IPS, which equals 16.51 m/s. Four CPI steps are available in total: 400, 800, 1600, and 3200.

All testing was done on the latest firmware (1.06). As such, results obtained on earlier firmware versions may differ from those presented hereafter.

CPI Accuracy

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 moderately high, which is a good result overall. In order to account for the measured deviation, adjusted steps of 400, 750, 1550, and 3100 CPI have been used for testing.

Motion Delay

Wired testing

First, I'm looking at two xCounts plots—generated at 1600 and 26,000 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." As you can see, neither plot shows any, which strongly suggests there not being any smoothing.


The XM2w 4K also allows enabling MotionSync, which tightens SPI timing.



In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 26,000 CPI. The line further to the left denotes the sensor with less motion delay. Without MotionSync, the XM2w 4K is slightly ahead of the G403 at both 1600 and 26,000 CPI, further confirming there not being any smoothing. With MotionSync, the XM2w 4K is now slightly behind.

Wireless testing


Compared to wired, SPI timing jitter is unchanged, as the sensor run mode continues to be set to corded. Upon enabling MotionSync (second row), SPI timing jitter is reduced yet again.



Once again, 1600 and 26,000 CPI are tested, both without (first row) and with (second row) MotionSync. Without MotionSync, the XM2w 4K is ahead by 1.0 ms. With MotionSync, this advantage is reduced to roughly 0.3 ms.

Speed-related Accuracy Variance (SRAV)

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

I've only managed to hit a measly 5 m/s, which is within the proclaimed PCS range and causes no observable sensor malfunction.

Polling Rate Stability

Wired testing

1000 Hz is fully stable.

Wireless testing
For wired mice, polling rate stability merely concerns the wired connection between the mouse (SPI communication) and USB. For wireless mice, another device that needs to be kept in sync between the first two is added to the mix: the wireless dongle/wireless receiver. I'm unable to measure all stages of the entire end-to-end signal chain individually, so testing polling-rate stability at the endpoint (the USB) has to suffice here.


First, I'm testing whether SPI, wireless, and USB communication are synchronized. Any of these being out of sync would be indicated by at least one 2 ms report, which would be the result of any desynchronization drift accumulated over time. I'm unable to detect any periodic off-period polls that would be indicative of a desynchronization drift, though bouts of elevated noise show up occasionally.


Second, I'm testing the general polling-rate stability of the individual polling rates in wireless mode. Running the XM2w 4K at a lower polling rate can have the benefit of extending battery life. 1000 Hz is generally stable, but bouts of elevated noise show up occasionally.

Paint Test

As you can see, no issues with angle snapping can be observed. There is no jitter visible at 1600 CPI. 26,000 CPI shows major jitter, which is only marginally reduced upon enabling smoothing (ripple control). Lastly, there is no lens movement.

Lift-off Distance

The XM2w 4K offers two pre-defined LOD levels. On the "1 mm" setting, the sensor will not track at a height of one DVD (<1.2 mm), whereas on the "2 mm" setting, the sensor will track at a height of one DVD, but not at a height of two DVDs (1.2<x<2.4 mm; x=LOD height). Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

In wired mode, click latency has been measured to be 0.4 (0.42) ms, with standard deviation being 0.23 ms. In wireless mode, click latency has been measured to be 0.4 (0.36) ms, with standard deviation being 0.13 ms. Polling rate has no effect on click latency.

Please note that the result given above only accounts for firmware-level latency. Physical latency, which describes the act of physically actuating the switch, is not accounted for, but that is precisely what is modified by enabling GX Speed Mode. Thus, in order to measure the difference between the GX Safe Mode/Off and GX Speed Mode settings, the end-to-end-latency function of LDAT has been employed, and the result is a relative difference of 1.45 ms. Relative to the measured click latency of 0.4 (0.36) ms, we thus arrive at a negative value of -1.1 ms, which of course is not a depiction of actual latency, but rather the result of mixing two sources of latency. In practice, however, the XM2w 4K will indeed be faster by the indicated amount compared to the other listed mice.

The main button switches were measured to be running at 3.27 V. I'm not aware of the voltage specifications of the used Kailh GX switches, but consider it likely that these are running within specifications.