Sensor and Performance

The Cooler Master MM310 is equipped with the PixArt PAW3327. According to specifications, the 3327 is capable of up to 6200 CPI, as well as a maximum tracking speed of 220 IPS, which equals 5.59 m/s. Through the software, an interpolated maximum CPI of 12,400 can be set. Out of the box, six pre-defined CPI steps are available: 400, 800, 1200, 1600, 3200, and 6200.

All testing was done on the latest firmware (1.04). As such, results obtained on earlier firmware versions may differ from those presented hereafter.

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 all over the place, which is a subpar result overall. In order to account for the measured deviation, adjusted but still off-target steps of 400, 800, 1600, and 3300 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 without special equipment, it is done by comparison with a control subject that has been determined to have consistent and low motion delay. In this case, the control subject is a Logitech G403, whose 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 6200 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." Given that the 3327 has no fixed framerate levels, no transitions show up either way, which is why the absence of any kinks in the second plot is not indicative of anything.


In order to determine motion delay, I'm looking at xSum plots generated at 1600 and 6200 CPI. The line further to the left denotes the sensor with less motion delay. Results weren't entirely consistent. At 1600 CPI, I can measure a motion delay differential of roughly 1.5–2 ms, whereas at 6200 CPI, a differential of roughly 4-4.5 ms can be measured. Typically, the 3327 has 2 ms worth of smoothing at and above 5100 CPI, which I assume to be the case here as well.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or SRAV). 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 causes no observable sensor malfunction.

Polling Rate Stability

Of the available polling rates (125, 250, 500, and 1000 Hz), only 1000 Hz looks and performs fine, while all the others show periodic outliers. Polling stability is unaffected by any RGB lighting effect.

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. There is no jitter visible at 1600 and 3200 CPI. 6200 CPI has smoothing applied and shows minor jitter. Lastly, there is no lens movement.

Lift-off Distance

The MM310 does not allow for LOD adjustment. This is expected, as the 3327 lacks this functionality. 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=LOD height). Keep in mind that LOD may vary slightly depending on the mousing surface (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.

Using a debounce time of 1 ms, click latency has been measured to be 3.9 ms, with standard deviation being 0.60 ms. Using a debounce time of 2 ms, click latency has been measured to be 8.0 ms, with standard deviation being 0.67 ms. Finally, using a debounce time of 6 ms, click latency has been measured to be 23.8 ms, with standard deviation being 0.61 ms.