CORSAIR K55 RGB PRO XT Gaming Keyboard

👤by Tim Harmer Comments 📅30-03-21
Software and Lighting.

Home Screen for iCUE v4 with quick 'scene' lighting, sensor and profile selection

CORSAIRís iCUE software was updated on March 16th to version 4, bringing significant changes to the UI to make it more approachable and easier to manage multiple iCUE devices. The good news is that v3 profiles are compatible with v4; any meticulously created lighting effects and key assignments will not be lost in the update.

Despite the UI change, the underlying organisational approach when configuring keyboard options remains the same:

Key Assignment configuration

Key Assignments:

Software-defined and controlled key assignments made on a per-key basis. Does not apply on other PCs, nor when iCUE isnít running.

Hardware Key Assignments:

Assignments stored in keyboard memory. Is the default behaviour when connected to systems without iCUE software installed, and only appears for keyboards with on-board profile memory. Not present for the K55 RGB PRO series.

Lighting Effects:

Software-defined and controlled lighting. Allows linked iCUE lighting across multiple devices.

Hardware Lighting Effects:

Lighting effects stored on the keyboard. Will apply when connected to systems without iCUE installed.

Performance tab with Device Settings activated

Each of these is stored on a per-profile basis, alongside device configuration information defined under the Performance and Device Settings tab. The number of software profiles available is effectively without limit, but the keyboard has no on-board profile functionality.

All attached iCUE devices are listed at the top as an image, and profiles are coherent across each of them. One-button profile switching will then apply to your entire iCUE peripheral set, both lighting and button assignments.

Key Assignment configuration

A frequently overlooked aspect of iCUE when it comes to peripheral control and configuration is the Dashboard panel. Here you can visualise all the system sensors - CPU Temp, GPU Fan RPM, Motherboard Sensors etc - in one convenient location. iCUE also has logging functionality, but we remain surprised that it's not easily accessed through this tab. Optionally, you can also add a list of every active key assignment on attached peripherals (the K55 RGB PRO XT in this instance).


In contrast to other K-series keyboards, the K55 RGB PRO XT has no on-board hardware profiles and only limited lighting customisation options when not attached to a PC running iCUE. Hardware button assignments transferable between PCs are limited to the six G keys, and the keyboard will store the G-Key macro assignments of the last active software profile.

Macros recorded through the on-board ĎMí key function can be edited through iCUE software to precisely modify timings, or created from scratch.

Alternatively, if Elgatoís Stream Deck software is running, the G keys can be assigned to one of any number of Stream Deck commands including community-sourced functions built from the SDK. This may be the best use of the G-Keys overall as the functions mitigate against the weaknesses of rubber-domed switches.


The K55 RGB PRO XT diverges a little from CORSAIRís previous per-key backlighting designs having the lighting shine through the entire plastic backplate rather than just the key switches. The backplate acts as a diffusion medium, evening out each bright single light source so it blends with neighbouring sources. None the colour vibrancy of each LED is lost in the process.

Backlighting for the XT model specifically is per-key rather than zonal, but requires iCUE to configure and process. In other cases it can default to one of 10 pre-configured lighting effects encompassing the entire keyboard, including full-RGB rainbow or static single-colour.

The diffuse nature of the backlighting rewards blocks of colour (2x2 LEDs or more) over single LEDs. More subtle effects of one or two LEDs tend to get lost in a pool of colour, and will be discoloured slightly by the light around them. For example a single red LED surrounded by blue will appear as a patch of blueish-purple under the selected key.

That being said, the underglow effect is more impressive than it sounds. Colours are still rich and vibrant, and the appearance is one of continuous colour banding rather than point lights. The most compelling lighting effects are ones that flow as blocks or bands of colour rather than single pixels, such as Visor and Rainbow defaults. On the other hand ĎRainí effects are less easy to pick as they rely on drawing a contrast between single pixels and a uniform background.

We should also say that the appropriate choice of keycaps allows light to shine through unobstructed, which isnít always the case on membrane keyboards.

An area notably absent any lighting is the glossy top area and media keys. An illuminated logo at least would serve to balance the keyboard well, and none on the media keys can make them a little difficult to read in low-light conditions.

iCUE lighting customisation is effectively the same as in the previous iCUE version despite the changes to a new software version. Itís based on layers, where each layer defines simple per-key effects, and layers are then stacked together to construct an overall dynamic lighting scheme.

Varying opacity over time can allow layers underneath to dominate, for example you can have a rain effect on top of a static colour backdrop isolated specifically to the numberpad, and then a Visor band going across the whole keyboard. From these simple rules you can build up immensely complex lighting programs that may even change with CPU temperature, act as an audio visualiser, or react to in-game events.

iCUE settings can also be imported from community repositories and saved for later use. Thatís another reason why CORSAIRís deep penetration into the peripheral market can be to your advantage.

For the K55 RGB PRO XT therefore, unlike other recent CORSAIR keyboards tested, installation and continuous use of the iCUE software massively unlocks the full functionality of the keyboard in a manner that cannot be replicated when not attached to a PC running iCUE. Pre-baked effects are all well and good but shouldn't be your main reason for choosing this model.

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