Sensor and Performance

The SteelSeries Prime is equipped with the TrueMove Pro, which I believe to be a PixArt PMW3389 with a custom SROM. According to specifications, the TrueMove Pro 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, 1200, 2400, and 3200.

All testing was done on the latest firmware. 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 consistently positive and fairly low. A good result overall. In order to account for the measured deviation, adjusted and largely on-target steps of 400, 800, 1550, 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 G403, whose 3366 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 18,000 CPI—to quickly gauge whether there is any smoothing, which would be indicated by any visible "kinks." As you can see, such kinks are on display in the second plot, which indicates there being smoothing. SPI timing jitter is remarkably low.


In order to determine motion delay, I'm looking at xSum plots generated at 1600, 4950, and 5000 CPI. The line further to the left denotes the sensor with less motion delay. There is no motion delay differential at 1600 CPI and 4950 CPI. At and above 5000 CPI, smoothing is applied for the first time, resulting in a motion delay differential of 3.5 ms, which holds true all the way until 18,000 CPI.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (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 4.5 m/s, which is within the proclaimed PCS range and results in no observable sign of the sensor malfunctioning.

Polling Rate Stability

All of the available polling rate settings (125/250/500/1000 Hz) look and perform fine. Polling stability is unaffected by any of the available 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. The little jitter visible at 4950 CPI is taken care of at 5000 CPI, where smoothing is first applied. 18,000 CPI shows major jitter despite the smoothing. Lastly, there is no lens movement.

Lift-off Distance

The Prime does not have any LOD adjustment options. This is unfortunate as the 3389 would be fully capable of it. By default, the sensor does not track at a height of 1 DVD (<1.2 mm). Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

Most gaming mice use mechanical switches for their buttons. By wiring the switches of the test subject together with the switches of a control subject, I'm able to measure click latency very accurately; i.e., standard error of around 0.05 ms. However, this method is not applicable to mice with non-mechanical switches and wireless-only mice in general. As such, other methods ought to be employed, one of which is NVIDIA's Latency Display Analysis Tool (LDAT). The LDAT allows me to measure the entire end-to-end latency between the mouse click and photon transition on the monitor. By establishing the relative difference to a control subject, I'm able to provide values I consider sufficiently accurate; i.e., standard error of around 0.2 ms. Many thanks go to NVIDIA for providing me an LDAT v2 device.

Click latency has been measured to be roughly +8.5 ms when compared to the Razer Viper 8K, which is considered as the baseline with 0 ms. Standard deviation is 2.4 ms, but since the indicated value is neither the absolute click latency nor the measured end-to-end-latency, standard deviation ends up looking disproportionally large. Comparison data comes from my own testing and has been exclusively gathered with the LDAT.