Tests And Performance
The ZM-K700M has two modes of key rollover: Z-key and N-key. Modes can be switched at anytime, although there is a one to three-second period when the keyboard will be unresponsive, so changing during the heat of battle is not recommended. When Z-key mode is activated, the RGB LED behind the Zalman logo on the right side of the keyboard will turn on, giving users an easy visual to determine what mode the keyboard is currently in.
Z-key mode is mainly for gaming, and it makes use of all the keyboard's features, whereas N-key mode is the standard mode for general purpose use. N-key mode via USB supports only the standard key repeat speed, and the function keys are unusable.
When I tested the keyboard in Windows 10, I was able to get N-key rollover via PS/2 in both N-key and Z-key modes, though over USB I was able to achieve 6KRO only while in N-Key mode.
I also tested the ZM-K700M on my Asus laptop with Ubuntu 14.04 and was able to achieve N-key rollover with Z-key mode active. Just as in Windows, I achieved 6KRO only when the keyboard was set to N-key mode. I was unable to test the keyboard on Ubuntu via PS/2.
When I plugged the ZM-K700M into my mid-2010 MacBook Pro with Yosemite 10.10.4 to test compatibility and rollover, I was not able to get the keyboard to work at all. The entire keyboard would slowly flash, and I was prompted with a window to determine what keyboard was plugged in. The end result was always the same "Keyboard not recognized" message. This was the only OS X-based computer I was able to test the keyboard on, but in the very least I will not recommend the ZM-K700M to Apple users at this time.
As you can hear in the test, there is still a noticeable "clack" when the switch bottoms out and the bottom of the keycap hits the top of the switch, even though the switch isn't clicky. The noise seems comparable in volume to the average rubber dome or laptop keyboard and shouldn't be an issue, even in quiet settings.
Should the noise of the MX Red switches bottoming out still be too noisy, you can put o-rings on the underside of the keycaps to prevent the plastic-on-plastic contact that results in the "clack" when you press a switch.