Sensor

Even though the specifications say the mouse uses a PixArt A3325, such a thing doesn't exist. The sensor is the PMW3325, a mid-level optical sensor. It's fine for casual use, and I would even recommend it for competitive gaming, but I know a lot of people might disagree. Until recently, the Avago A3050 was king in the low price range as it provided acceptable performance and is very affordable. Years have gone by, and the PMW3325 is slowly but surely taking its place even though it's a tad pricier.

Specifications state this sensor to have nominal acceleration and maximum tracking speeds of 20 G and 100 IPS (2.54 m/s), but in reality, these values are much higher. For some reason, Cooler Master also only specifies 60 IPS tracking speed on the product website, which is clearly false.

You can set the resolution to 500, 1000, 2000, 4000, 3000, 5000, and 10,000 CPI. Unfortunately, only these pre-defined steps are available, so you can't set 800 CPI, for instance. As for the polling rate, it is set to 1000 Hz without the ability to change it (my CM310 model is an early copy set to 500 Hz, but the commercially available ones are running on 1000 Hz), which translates to 1 ms of response time. There is no way to adjust the lift-off distance with this sensor, and it's a tad higher than on high-end sensors. The sensor easily tracks from 1 DVD height, but doesn't from 2 DVDs, which means the actual LOD is set to somewhere around 2 mm.

Paint Test

There is no jitter on the reasonable CPI steps, and I couldn't detect any sensor rattle either. There is minor angle snapping (or I just suddenly became very good at drawing straight lines, which I highly doubt), but it's not as harsh as with some older sensors, so it shouldn't be much of an issue for most people. Once again, this mouse isn't really built for absolute mouse enthusiasts or top eSport competitors, so things like this are mostly acceptable.

CPI Divergence

Thankfully, CPI divergence on this mouse is low compared to most newer gaming mice. The divergence is negative, which means you might need to increase your in-game sensitivity a little bit if coming from a mouse with pitch-perfect CPI accuracy. Please note that this measurement is not 100% accurate as there is some human error involved, but the values resemble reality well.

Perfect Control Speed

Perfect control speed (or PCS for short) is not the highest on this sensor, although it should definitely be enough for the target group. It stops tracking at about 3.6 m/s, which usually means a very fast swipe on a large mouse pad. Upon reaching the maximum speed, the sensor doesn't spin out, so you won't see the sky or your legs in-game; it'll just stop tracking at a certain position. The PCS doesn't correlate with the set CPI, which means 500 and 10,000 CPI both reach their limits at the same speed.

Speed Related Accuracy Variance

This test shows the sensor's accuracy at different speeds. You can see me doing a fast swipe to the right before I slowly slide the mouse back to its original position. There is pretty much no acceleration or deceleration. The minor displacement in this test is most likely caused by human error.

Polling Rate

The polling rate is nice and stable and doesn't suffer from any periodic drops or strange outliers. As I've mentioned before, the commercially available CM310 operates at 1000 Hz; mine is an initial reviewer-copy without the upgrade to 1000 Hz.

Input Lag & Smoothing

Even though the xCount graphs indicate otherwise, I could measure about 2-3 ms of input lag on each and every CPI step. This might be a firmware-related issue or can be intentional smoothing to make mouse movement less snappy and smoother, which might appeal to casual users (it might also be related to angle snapping, but I am really not sure about this).

Click Latency

Click latency is roughly +18.8 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. The data comes from this thread and my own testings. Testing was done with a Logitech G100s and the CM310, using qsxcv's program. This is an unusually high amount of click latency, and I've notified Cooler Master. It can be intentional though, in order to reduce chances of accidentally double clicking (which is a common fault of micro switches and can appear after even a few weeks of use).