Sensor and Performance

The Razer Basilisk V3 X Hyperspeed is equipped with the PixArt PAW3369, which I believe to be a customized PAW3335. According to specifications, the 3369 is capable of up to 18,000 CPI, as well as a maximum tracking speed of 450 IPS, which equals 11.43 m/s. Out of the box, five pre-defined CPI steps are available: 400, 800, 1600, 3200, and 6400.

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 very high, which is a subpar result overall. In order to account for the measured deviation, adjusted steps of 350, 750, 1500, and 3000 CPI have been used for testing, which provide near-perfect CPI accuracy.

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 Logitech G403, whose PixArt PMW3366 sensor has no visible smoothing across the entire CPI range. Note that the Basilisk V3 X Hyperspeed is moved first and thus receives a slight head start.


First, I'm looking at two xCounts plots—generated at 1600 and 18,000 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." The second plot plainly shows such kinks, strongly suggesting there being smoothing.


Of particular note are outliers showing up when moving the mouse at reasonably high velocity, which directly correspond to off-period polls. This happens regardless of which type of port the dongle is plugged into (directly into 2.0, through extender plugged into 3.x), and regardless of whether RGB lighting is enabled.


In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 18,000 CPI. The line further to the left denotes the sensor with less motion delay. At 1600 CPI, I can measure a motion delay differential of roughly 1 ms. The first level of smoothing is applied at and above 6200 CPI, resulting in a motion delay differential of roughly 4 ms, whereas the second level is applied at and above 11,700 CPI, resulting in a motion delay differential of roughly 8 ms, which holds true all the way to 18,000 CPI.


Much like on many other recent Razer mouse releases, occasionally a shift occurs at some point of the motion, which increases motion delay by a full interval past that point.

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 5 m/s, which is within the proclaimed PCS range and shows no sign of the sensor malfunctioning.

Polling Rate Stability

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 able to detect several off-period polls, which may be related to a desynchronization drift.


Second, I'm testing the general polling-rate stability of the individual polling rates in wireless mode. Running the Basilisk V3 X Hyperspeed at a lower polling rate can have the benefit of extending battery life. All of the available polling rates (125, 500, and 1000 Hz) show irregular off-period polls. In addition, 1000 Hz displays generally increased noise at times. Take note of how the polling changes throughout the motion, which has been performed at a near-constant velocity of 0.1-0.2 m/s:


I'm unable to reproduce this behavior consistently.

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. 6150 CPI is the highest step without smoothing and shows moderate jitter, which is lessened by the smoothing first introduced at 6200 CPI. 18,000 CPI shows major jitter despite the second level of smoothing being applied. Lastly, there is no sensor lens movement.

Lift-off Distance

The Basilisk V3 X Hyperspeed offers two pre-defined LOD levels to choose from, along with the ability to select a pre-calibrated Razer surface. Using the "1 mm" preset, the sensor does not track at a height of 1 DVD (<1.2 mm). When using the "2 mm" preset, the sensor does track at a height of 1 DVD, but not at a height of 2 DVDs (1.2 mm<x<2.4 mm, x being LOD height). Keep in mind that LOD may vary slightly depending on the surface (mouse pad) it is being used on.

Click Latency

In most computer mice, debouncing is required to avoid double clicks, slam-clicks, or other unintended effects of switch bouncing. Debouncing typically adds a delay, which, along with any potential processing delay, shall be referred to as click latency. In order to measure click latency, the mouse has been interfaced with an NVIDIA LDAT (Latency Display Analysis Tool). Many thanks go to NVIDIA for providing an LDAT device. More specifically, the LDAT measures the time between the electrical activation of the left main button and the OS receiving the button-down message. Unless noted otherwise, the values presented in the graph refer to the lowest click latency possible on the mouse in question. If a comparison mouse is capable of both wired and wireless operation, only the result for wireless (2.4 GHz) operation will be listed.

Click latency has been measured to be 2.4 ms, with standard deviation being 0.24 ms.

The main button switches were measured to be running at 1.902 V. I'm not aware of the voltage specifications of the Kailh GM 4.0 (60 M) switches, but 1.902 V does seem rather low to me, albeit not excessively so.