Gaming keyboard manufacturers, much like gaming mice manufacturers, claim fast response times to entice games to pay the premium. Unlike gaming mice, however, we do not find enough benchmarks that have actually put the claims to test. As a result, gamers and enthusiasts have (until now) gone by the manufacturer's claims of high polling rates and low response times. So is that shiny new RGB keyboard with anti-ghosting or N-key rollover actually more responsive than a conventional keyboard? Dan Luu's mini-experiment proves otherwise.

Introduction

It might seem astonishing but modern keyboards have a 20x denser transistor count than the Intel 8080 microprocessors, which powered entire PCs in the 1970s. It is human tendency to assume that any modern peripheral would be faster than the previous generation by several orders of magnitude, but it turns out that it is actually not true. Despite the higher transistor count and faster clocks than first generation PCs, modern keyboards actually have high key press latencies compared to the entire key press pipelines from yesteryear computers.



When on the lookout for a high-end PC, keyboards are often given the after-thought. Except for enthusiasts no one actually spends time in perusing the keyboard specifications. Those on the lookout for purchasing gaming hardware will generally find themselves to be drawn towards keyboard latency and the mechanical nature of pro-gamer keyboards. It is also a common perception that keyboards having high polling rates are better suited for gaming given their perceived low input lag and low response times. So do response times and polling rates matter when in the hunt for a good gaming keyboard or is it just a marketing gimmick? Do PS/2 keyboards of yore actually have better performance compared to today's 'low latency' USB high speed ones? Ex-Microsoft engineer Dan Luu's little experiment might just have the answer.

Before we move to learn more about this interesting study, let us familiarize ourselves with some jargon.

Polling Rate - The rate at which the computer checks the USB bus for data. A keyboard having a 1000Hz polling rate is queried by the host CPU 1000 times a second or 125 times every 8ms. The OS knows the polling rate of the device when the device first registers itself on the USB bus. Although not an issue with modern processors, high poll rates do take up considerable CPU resources.

Matrix Scan Rate - This is the rate at which the keyboard's microprocessor scans the entire keyboard matrix (the rows and columns of keys) to see which key has been pressed. If it detects a key press — basically a binary 0 — it registers the input and sends it to the host. The rate at which the keyboard matrix is scanned depends on the firmware and is generally not visible to the end user.