Sensor and Performance

The Razer Cobra is equipped with the PixArt PAW3349. According to specifications, the 3349 is capable of up to 8500 CPI, as well as a maximum tracking speed of 300 IPS, which equals 7.62 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 all over the place, which is a subpar result. In order to account for the measured deviation, adjusted steps of 350, 750, 1500, and 3100 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.


First, I'm looking at two xCounts plots—generated at 1600 and 8500 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. SPI timing jitter is relatively low.


In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 8500 CPI. The line further to the left denotes the sensor with less motion delay. There is no motion delay differential at 1600 CPI. At 8500 CPI, a motion delay differential of 2.5–3 ms can be measured, suggesting there being smoothing after all. That said, I have a hard time determining the exact point at which it is introduced. According to Razer, smoothing is first applied at 3250 or 3300 CPI, but I haven't been able to ascertain any motion delay differential between 3200 and 3300 CPI, which is curious.

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

All of the available polling rates (125, 500, and 1000 Hz) are fully stable. Polling stability is unaffected by any RGB lighting effects.

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. 3000 CPI already shows minor jitter, which is amplified further at 5000 CPI, reaching major levels at 8500 CPI, despite the smoothing applied at that step. Lastly, there is no sensor lens movement.

Lift-off Distance

The Cobra offers no pre-defined LOD levels. By default, the sensor does not track at a height of 1 DVD. That said, Synapse offers various pre-calibrated Razer surfaces to choose from, which may result in an accordingly higher or lower lift-off distance if used in conjunction with a different surface. 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 0.9 ms, with standard deviation being 0.38 ms.