Our initial impression when the Cooler Master MM830 gaming mouse launched was that the OLED seemed like no more than a bauble, while the d-pad built into the left-side thumb rest was actually a promising feature. Now that we've had a chance to spend some quality time with CM's latest and greatest mechanical rodent, we have clarity on both of those items.
In addition to a startling number of "M"s in its name, the CM MM830 sports a PixArt 3360 optical sensor that's capable of 100-24,000 DPI, which is about 5x more than anyone will ever use. There's no acceleration, but it does have angle snapping (which you can disable), and the lift-off distance is adjustable up to 2 mm. You can store up to four profiles on the 512 KB of onboard memory.
The MM830 is a right-handed gaming mouse, not quite ergonomic per se, but shapely. I have to say that I like the contour. The palm rest sits firmly in my hand, and the mouse is long enough that I can comfortably lay my fingers on the left and right click buttons. Note, though, that I have slightly large hands; if you have anything less than above-average-sized hands, you won't be able to use a claw grip on the MM830.
The exterior is PBT plastic, but it feels a little plasticy (not in a good way), and its surface is ever so slightly textured. I'm sure some people will like the change from a completely smooth surface, but I found it a tiny bit irritating to my fingertips after a long day of clicking. I also started seeing a small amount of wear after just a day or so. It's not as pronounced as what I've seen on some other black plastic mice, and it didn't seem to get worse as the days wore on.
The MM830 is balanced. It's not a light mouse per se; Cooler Master has it listed at 162 g with the cable, but it feels much lighter, closer to the 122 g sans cable that's in the spec sheet. The lightness may partly be an illusion, because most of the heft is in the middle rather than the front or rear. This was a correct choice on Cooler Master's part, given that this mouse is so heavy and palm grip-friendly.
Subjectively, the left and right buttons feel a little heavier and have a more pronounced travel than I'm used to. That's not a bad thing. The scroll wheel is stepped rather than smooth, and it's rather light. Its placement is perfect for my finger length and hand size. Obviously that won't necessarily be the case for everyone else, but it certainly made me happy.
There's also a DPI button and the four d-pad buttons on the left side. There are no buttons on the right side. All of the buttons are programmable (except for the left click), as are the four lighting zones. There are separate lighting areas on the scroll wheel, behind the scroll wheel, and along the bottom edge of the palm rest. There's a glowing CM logo on the palm rest, too.
Underneath the mouse are three large feet for a smooth ride on multiple surfaces. On the left side, towards the front of the MM830, is an OLED display.
The utterly useless OLED display that is still kind of cool
We'll get into the weeds with the d-pad, but to be blunt up top: The OLED display on the MM830 serves no practical purpose. Ostensibly, it displays helpful information like in-game stats or the current DPI. You can also set it to display logos and such. The problem is, you can't see the screen when you're actually using the mouse, which defeats the purpose of having it in the first place.
I mean that literally. With the mouse sitting on my mousepad, I can't see anything that's displayed on the screen. If my torso was a foot shorter, I could see the screen with a quick askance glance. It's positioned such that your thumb won't occlude it—but that grown adults and especially tall children sit at too high an angle to see it.
That's not to say it isn't a neat feature. If you want to trick out your mouse for [reasons], this is a fairly unique way to do so. Just don't expect any practical benefit.