Sensor

The MM520 uses the current flagship of optical mouse sensors, the PixArt PMW3360. This is quite rare in this price segment. The implementation is very good; there is no floaty feeling as far as I could tell. It's very raw, responsive, and perfectly accurate. I didn't encounter any anomalies during my tests or in-game.

All previous Xornet and Spawn models used mediocre sensors and/or had below mediocre implementations, and they didn't perform quite as well because of it. It's nice to see that Cooler Master has caught on to this problem to then go with the top choice.

The resolution can be changed from 100-12,000 CPI, in increments of 100. The polling rate can be set to 125, 250, 500, and 1000. There are two lift-off distance settings, one marked as low and another as high. The low setting is about as high as a DVD, but it barely tracked on a black cloth pad.

Paint Test

As you can see, there is no noticeable jitter with the reasonable CPI steps. There is no angle snapping or measurable sensor lens rattle either.

CPI Divergence

The CPI accuracy was near-perfect. I couldn't measure any noticeable deviations with any of the defined CPI steps. Many mice out there suffer from some divergence here, but the MM520's settings match those you will actually get.

Perfect Control Speed

The sky is the limit. I don't think there's a way of actually reaching the PMW3360's PCS (perfect control speed) intentionally, or even unintentionally. It's very high, and there is no way you would accidentally hit it in-game. There is no data path limit, which means the PCS isn't getting cut at higher CPI steps.

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 some human error to this test, of course, but it shows that the SRAV is negligible in our case - just as one would expect it to be with this sensor.


Here's the same test done with the MouseTester software.

Polling Rate

All set values are correct and stable. Even though it may not seem like it, the results should actually look like this.

Input Lag

The control subject (blue) is a Ninox Venator at 800 CPI. In every single PMW3360 mouse I have tested so far, there is at least +2 ms of input lag right above the 2000 DPI setting. The MM520 isn't an exception. As you can see, the 2 ms instantly kicks in above 2000 DPI and stays there until the very top. If you play competitive games on a high level, I would advise you to stay below 2100 DPI.