Released earlier this year, the Endgame Gear OP1 8K served as proof that wired mice still have a place in the gaming mice market. Aside from its high-quality buttons, build quality, and low weight, the OP1 8K above all impressed with its outstanding performance, including having the lowest click latency of any mouse tested. As such, it comes as no surprise that the XM2 8K picks right up where the OP1 8K left off, and delivers the same internals in a different package.
At 51 g, the XM2 8K weighs only 2 g more than the OP1 8K, which is roughly in line with the difference in size. On my sample, build quality is just as good as it was on the OP1 8K: no rattle when shaking the mouse, no creaking or flexing of the shell when applying lateral pressure, and activating the side buttons by pressing below them is impossible. The cable likewise hasn't seen any changes, and continues to impresses with its flexibility, while retaining sufficient shielding to ensure signal integrity at 8000 Hz (or, more precisely, USB high-speed). The feet are of a similar type as the ones used on the OP1 8K, are made of pure PTFE, and glide very well. A set of replacement feet once again is included in the box, but unlike on the OP1 8K, a set of grip tape unfortunately no longer is, for reasons unknown.
Much like the OP1 8K, the XM2 8K still utilizes Kailh GX switches for the main buttons. Being so-called SPDT switches, these have an additional top contact alongside the regular bottom contact, which can be used for various things. One possible use is to employ this contact as an additional layer of hardware debouncing, in that a click will only be registered if the bottom contact is closed and the top contact not closed. Another and arguably the more thrilling use case is the so-called GX Speed mode, by virtue of which a click will be registered already when the top contact is no longer closed instead of waiting for the bottom contact to close, reducing physical latency in the process. In my testing, enabling GX Speed Mode reduces click latency by 1.4 ms compared to non-Speed modes, which is a highly substantial reduction. In short, nothing has changed compared to the OP1 8K in this regard, with one exception: the main button switches no longer are mounted on their own PCBs, and instead are soldered to the main PCB, thus not allowing easy replacement without soldering. Accordingly, the XM2 8K no longer has the screws at the bottom exposed, as that type of straightforward modding is no longer possible.
In terms of feel, the GX switches are also great. Actuation is very firm and snappy, although also on the stiffer side, despite the actuation force rating of 55-60 gf. The button design likewise is sound, as lateral movement is minimal even when provoked, pre-travel is moderate, and post-travel low. For the side buttons, another set of switches from Kailh is used, although these are GM 2.0. Pre and post-travel are low, albeit a bit higher on the back button, actuation is even, and button response pleasing. For the scroll wheel, a TTC Silver encoder sees use, though this time around, the encoder has been hooked to the top shell. Either way, it impresses with very nicely defined steps, allowing for controlled scrolling, even though noise levels are elevated. In short, the switch selection isn't any different from the OP1 8K.
Performance on the XM2 8K continues to be stellar. General tracking is great, polling stable all the way to 8000 Hz, and smoothing disabled by default, such that motion delay is the same across the entire CPI range. Speaking of, as long as MotionSync stays disabled, motion delay will be the same regardless of polling rate, sitting at a fantastic 1.2 ms advantage over the Logitech G403 (control subject). Enabling MotionSync adds motion delay of various degrees depending on polling rate, with 1000 Hz having the highest negative impact and 8000 Hz the lowest. Click latency likewise is unaffected by polling rate and comes out at an average of 0.1 ms, which is on par with the 8000 Hz wired offerings from Razer (DeathAdder V3/Viper 8K) or Zaunkoenig (M2K). Do keep in mind, however, that this number only accounts for firmware-level latency, as by enabling GX Speed mode, physical latency can be lowered by another 1.4 ms, placing the XM2 8K far ahead of the competition, and only matched by the OP1 8K.
The software is another strong point of the XM2 8K. Not only does it utilize no more than 2 MB of RAM, which in itself is a masterclass in efficient coding, it also doesn't require installation, all while having all the necessary options included. In fact, the range of settings goes beyond the standard, as one can also define the minimum click duration, which can be useful when trying to maximize CPS (clicks per second) for games such as Minecraft. In addition, CPI values can be set for the x and y-axis independently, and the slam-click filter, which prevents inadvertent clicks upon resetting the mouse, may be turned off as well.
The only flaw I could find related to performance concerns CPI deviation, and this is a most curious case. On my sample, I've measured a positive deviation of no less than +24% across the board, which is among the highest I've ever seen. This deviation persists regardless of settings, firmware, full resets/reflashes, or any other potential non-hardware cause. Looking through user reports, I've found that this is not an isolated case, and similar degrees of deviation are rare but do exist. A second sample provided by Endgame Gear for testing showed much lower deviation of +7.5%, though this is still higher than what I've measured on the OP1 8K. According to Endgame Gear, the reason for this deviation is as follows: one of the cavities for lens fusing has been faulty, resulting in the lens sitting lower than intended if the PCBA had not been placed exactly right, in turn resulting in large positive deviation. Endgame Gear has checked the remaining inventory and found only a small number of units affected, and the process has been optimized such that future units will not be affected. In any case, the only notable downside to this is the inconvenience associated with it. Essentially, when getting the XM2 8K, I would advise to first measure CPI deviation, and then adjust all steps to account for any possible deviation.
This bizarre CPI deviation issue aside, the XM2 8K is just as good as the OP1 8K, and provides those who found the OP1 8K too small or narrow a much sought after alternative. The only real complaint I still have concerns the coating of the black variant, which may be grippy but also a fingerprint magnet, and difficult to get fully clean, too. Thankfully, variants in white or with transparent shells are also available, so this minor gripe shouldn't deter one from getting the XM2 8K. Accordingly, the XM2 8K earns our Recommended award.
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