Sensor and Performance

The Razer Cobra Pro is equipped with the Focus Pro 30K (PixArt PAW3950). According to specifications, the Focus Pro 30K is capable of up to 30,000 CPI, as well as a maximum tracking speed of 750 IPS, which equals 19.05 m/s. Out of the box, five pre-defined CPI steps are set: 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 low, which is an excellent result. In order to account for the measured deviation, adjusted steps of 400, 800, 1600, and 3150 CPI have been used for testing.

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 G403 is moved first and thus receives a slight head start.

Testing is restricted to 2.4 GHz mode as Bluetooth is not suitable for non-casual gaming applications.

Wired Testing

First, I'm looking at two xCounts plots—generated at 1600 and 30,000 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. Owing to sensor-level MotionSync, SPI timing jitter is minimal.


Occasionally, however, outliers become visible, which are not related to polling. I'm unable to reproduce this behavior consistently.


In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 30,000 CPI. The line further to the left denotes the sensor with less motion delay. I can measure a motion delay differential of roughly 0.5 ms at 1600 CPI and 1 ms at 30,000 CPI.

Wireless Testing

Upon switching to wireless, not much changes, which is impressive.


Once again, 1600 and 30,000 CPI are tested. I can measure a wireless motion delay of roughly 1 ms at 1600 CPI and 2 ms at 30,000 CPI.


Much like on the Basilisk V3 Pro, DeathAdder V3 Pro, or Viper V2 Pro, when using the included full-speed dongle, a rather peculiar behavior may show up. Essentially, at some ultimately random point within the motion, a shift occurs, beyond which motion delay increases. I've only been able to demonstrate this behavior when using the included full-speed dongle at 1000 Hz in wireless mode. Unfortunately, I'm unable to assert what causes this behavior.

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

Considering the Cobra Pro is usable as a wired mouse as well, I'll be testing polling rate stability for both wired and wireless use.

Wired Testing

Of the available polling rates (125, 500, and 1000 Hz), 125 and 500 Hz are fully stable, whereas 1000 Hz shows the odd 2 ms poll, along with generally increased noise. Polling stability is unaffected by any RGB lighting effects.

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.


Second, I'm testing the general polling-rate stability of the individual polling rates in wireless mode. Running the Cobra Pro at a lower polling rate can have the benefit of extending battery life. Of the available polling rates (125, 500, and 1000 Hz), only 1000 Hz looks fine. In terms of performance, Razer has assured me that both 125 and 500 Hz are working as intended, despite not looking that way. In fact, 500 Hz in particular is said to be faster than many 1000 Hz implementations, which I've been able to corroborate. When using the HyperPolling Wireless Dongle instead of the included full-speed one, the plots look significantly different:

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. 15,000 CPI shows significant jitter, which is amplified to major levels at 30,000 CPI. This is in line with what to expect from a sensor lacking smoothing entirely. Lastly, there is no sensor lens movement.

Lift-off Distance

The Cobra Pro offers a wider range of possible LOD adjustment than most mice. One can set the LOD to pre-defined levels of low, medium, or high. Manual calibration is no longer present as the sensor already does this by itself. When using the "low" option, the sensor does not track at a height of 1 DVD (<1.2 mm), which doesn't change when using the "medium" option. When using the "high" setting, the sensor does track at a height of 1 DVD, but not at a height of 2 DVDs (1.2<x<2.4 mm, x being LOD height). Additionally, Asymmetric Cut-off can be enabled, which allows for a higher lift-off distance while keeping the landing distance low. 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.

In wired mode, click latency has been measured to be 1.4 ms, with standard deviation being 0.20 ms. In wireless mode and using the included full-speed dongle, click latency has been measured to be 0.9 ms, with standard deviation being 0.42 ms. When using the HyperPolling Wireless Dongle at a polling rate of 1000 Hz, click latency has been measured to still be 0.9 ms, but standard deviation is lower at 0.13 ms. When using the HyperPolling Wireless Dongle at a polling rate of 2000 Hz, click latency has been measured to be 0.5 ms, with standard deviation being 0.12 ms. Finally, when using the HyperPolling Wireless Dongle at a polling rate of 4000 Hz, click latency has been measured to be 0.5 ms, with standard deviation being 0.10 ms.