Sensor and Performance

The SteelSeries Aerox 9 Wireless is equipped with the TrueMove Air, which is a customized PixArt PAW3335. According to specifications, the TrueMove Air is capable of up to 18,000 CPI as well as a maximum tracking speed of 400 IPS, which equals 10.16 m/s. Out of the box, five pre-defined CPI steps are available: 400, 800, 1200, 2400, and 3200.

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 exclusively positive, inconsistent, and large. A poor result overall. In order to account for the measured deviation, adjusted steps of 400, 800, 1600, and 3000 CPI have been used for testing. Due to CPI adjustment not being linear, getting accurate steps of 400 and 800 CPI turned out to be completely impossible, only near-accurate 1600 and 3200 CPI steps could be achieved.

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.

Wired Testing

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." While the first plot shows no such kinks, the second one does, indicating there being smoothing.


In order to determine motion delay, I'm looking at xSum plots generated at 1600, 6200, and 18,000 CPI. The line further to the left denotes the sensor with less motion delay. For no apparent reason, 1600 CPI displays a motion delay differential of roughly 1 ms. 6200 CPI has the first level of smoothing, resulting in a motion delay differential of roughly 4 ms. 18,000 CPI has the second level of smoothing, which results in a differential of roughly 8 ms.

Wireless Testing

Not much changes upon switching to wireless, as SPI timing jitter and general tracking are virtually on the same level as when wired.


Once again, 1600 and 18,000 CPI are tested. Keeping the motion delay differential in wired mode established above in mind, I can measure a wireless motion delay of roughly 1 ms.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or short 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 4.5 m/s, which is within the proclaimed PCS range and causes no observable sensor malfunction.

Polling Rate Stability

Considering the Aerox 9 Wireless is usable as a wired mouse as well, I'll be testing polling rate stability for both wired and wireless use.

Wired Testing


All of the four available polling rates (125, 250, 500, and 1000 Hz), look and perform fine. Polling stability is unaffected by any RGB lighting effect.

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. The odd off-period poll is visible, which may be the result of a desynchronization drift.



Second, I'm testing the general polling-rate stability of the individual polling rates in wireless mode. Running the Aerox 9 Wireless at a lower polling rate can have the benefit of extending battery life. Aside from 1000 Hz, which shows the odd off-period polls, all polling rates look and perform fine, and polling stability is unaffected by any RGB lighting. Furthermore, in select cases, polling breaks down entirely for reasons unknown:

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. 6100 CPI shows minor jitter, which is largely taken care of at 6200 CPI, where smoothing is first applied. 18,000 CPI displays moderate to major jitter. Lastly, there is no lens movement.

Lift-off Distance

The Aerox 9 Wireless does not offer any LOD adjustment options. This is unfortunate as the PAW3335 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

In most computer mice, mechanical switches are being used for the main buttons, which require debouncing in order to avoid unintended double clicks. Debouncing typically adds a delay (along with any potential processing delay), which shall be referred to as click latency. As there is no way to measure said delay directly outside of using a USB analyzer, it has to be done by comparing it to a control subject, which in this case is the ASUS ROG Chakram Core. The test setup involves wiring the NO pin of one of the main button switches of the test subject to one of the control subject, and qsxcv's program is used to measure the relative delay between them. Doing so is only possible if the devices in question are plugged into the PC through a wired connection. The Zaunkoenig M2K has been posited as the baseline for being within 0.1 ms of the possible minimum click latency of a high-speed device and within 0.2 ms of a hypothetical absolute minimum. As such, the resulting values may be considered quasi-absolute.

Click latency has been measured to be roughly +6.9 ms, with standard deviation being 0.90 ms.

The main button switches were measured to be running at 1.934 V. I'm not aware of the voltage specifications of the TTC Golden Micro Dustproof (80 M) switches, but find this voltage to be rather low.