Razer Lachesis Review

If you're a left-hander looking for a gaming mouse we'd say the Lachesis is a no-brainer.
If you're a left-hander looking for a gaming mouse we'd say the Lachesis is a no-brainer.
If you're a left-hander looking for a gaming mouse we'd say the Lachesis is a no-brainer.


  • Extreme sensitivity levels; ambidextrous; comfortable


  • Firmware update issues; on-the-fly sensitivity feature didn't always work

DT Editors' Rating

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The Lachesis is the world’s largest pit viper snake, and the word means “Bringer of Silent Death” in Latin, according to Razer. In reality it brings comfortable mousing to both left-and-right handed gamers, but that’s a decidedly less sexy tagline. The biggest selling point of the Lachesis is that it offers 4000dpi sensitivity, which is the highest so far in the dpi arms race. Though its 4000 dpi was a bit too sensitive for our tastes and we had a few issues with the software, it’s still an overall decent product from Razer.

Features and Design

The Razer Lachesis is an ambidextrous mouse, which is interesting since lefties are usually left out of the gaming mice party. Most of Razer’s mice are for right-handers, as are all of Logitech’s G-series mice.

The Lachesis is somewhat long, but flatter than most mice. It has a sort of “low rider” profile in our opinion where your hand rests on top of it, rather than having your palm grip it like a Logitech mouse.

It’s a nine-button mouse that is symmetrically designed. It features a left-and-right click button, two navigation buttons per side, a clickable mouse wheel and dpi adjustment buttons. It features on-the-fly dpi switching that is customizable and lets you establish five dpi increments.

The mouse has a two glowing parts – the mouse wheel and a pulsing Razer logo on top of the palm rest. Both can be disabled, and you can choose to buy a Lachesis with either a blue light or a white light.

As always, every button on the Lachesis can be customized. You can also create profiles that are paired to certain games, and set the profile to automatically become active when a pre-selected game starts. The maximum dpi is a scorching 4000, which is the highest available for any mouse (Logitech’s G9 Laser only goes up to 3200).

The Lachesis also has 32kb of onboard memory for storing up to five profiles, so you can have all your favorite settings handy if you move the mouse to a new PC (like at a LAN party, or in case you lose your PC to a house fire).

Razer Lachesis
Image Courtesy of Razer

Use and Testing

Unlike most mice packages that just give you the mouse and a software CD, Razer throws in a few stickers that you can put on your chassis. We took the mouse out of the box and were impressed by the seven-foot USB cable, which is great for people (like us) who have huge desks.

We plugged in the Lachesis and installed the Razer software. Like any USB mouse, you don’t have to install the software to get the mouse to work in Windows, but you’ll need to use the software if you want the full functionality of the mouse.

We used the mouse for approximately two weeks and came away impressed by its accuracy and comfort. It honestly took about three days to get used to, however, as we were not used to using a mouse this sensitive. We like the customizable dpi settings, which let you determine what the sensitivity will be when you push the dpi adjustment button You can set the sensitivity anywhere between 500 and 4,000 dpi, which is great. You can also adjust the polling rate of the mouse, but you have to reboot in order for it to take affect. We found that 4,000dpi was way too sensitive, but it’s nice to have the option.

Software Control

The amount of customization available through the software is almost overkill, as you can do a million different things to customize the mouse. In addition to setting up different profiles for different applications, you can tweak the sensitivity of individual axes of the mouse, change button assignments, double-click speed, make macros and much more.

Though we had no problems setting up different profiles and adjusting sensitivity settings, we ran into two issues with the software that were reminiscent of our last experience with a Razer mouse. The first was that we were had a confusing experience when trying to update the firmware on the mouse. We ran the software and it said it was updated, and that all we had to do was unplug and reconnect the mouse. We did so and the software told us we were still using version 1.0 instead of version 1.64. We tried re-installing the firmware but were told the firmware was the same version as the one we were installing. We looked in the manual but it just said to go online for the latest updates. On a lark we rebooted, and that successfully updated the mouse’s firmware, but it would be nice if Razer provided more explicit instructions about this process. We had similar firmware installation issues last time, and we wish Razer would make this process easier as there’s no reason for it to be this confusing.

Razer Software Screenshot
The Razer software offers a wide range of adjustments for every facet of the mouse.

We also could not get the on-the-fly sensitivity to work every time. In theory, you assign it to a button and then press the button and a little meter pops up on the screen. You can then use the mouse wheel to adjust sensitivity up and down, but we couldn’t get this feature to work. We assigned it to every button on the mouse except one, and it just didn’t work. Even after we updated the firmware this feature still did not work for some reason.


We like the Lachesis a lot due to its comfort and features. It’s disappointing to see continued software issues though, and we would like to see Razer make the updating process simpler. If you’re a left-hander looking for a gaming mouse we’d say the Lachesis is a no-brainer. For right-handed mousers however, it’s not quite as clear-cut.


• Extreme sensitivity levels
• Ambidextrous
• Comfortable


• Firmware update issues
• On-the-fly sensitivity feature didn’t always work