About Key Rollover And Ghosting
Key rollover and ghosting are two of the more important factors of a keyboard’s real performance. Insufficient rollover results in missing key inputs, while ghosting occurs when two or more depressed keys cause a third “phantom” keystroke to be activated. Considering that the keyboard’s primary function is to serve as a go-between for you and the system itself, anything that can cause interference is pretty important when benchmarking these things.
Most consumer keyboards typically use a grid system for determining which keys you’re pressing. For most, this is enough, as only awkward combinations like the letters “T+H+G” pressed all at once would cause a failure. In gaming, however, things get a bit dicey. A common sequence in a first person shooter, for example, would be “Shift+W+R” corresponding to crouching while moving forward and reloading a weapon. “W” and “R” almost always share a horizontal row, but because they are typically on separate vertical columns, that alone wouldn’t be too big of a deal. Sometimes, though, “Shift” and “W” will share a vertical row (it sounds weird but that’s the case with one of our old laptops), which will, in turn, cause a keyboard to misread the press.
As a general rule, mechanical keyboards have become popular with gamers, specifically because they tend to isolate key presses by using a distinct switch for each and every key. Instead of shorting an entire row or column, all of the keys can be more or less reliably detected, allowing all the input to be relayed back to the computer. With more and more games being played competitively in the world of eSports, it’s no wonder so many are turning to more reliable equipment.
That said, each of these devices uses a USB interface instead of PS2, meaning that an on-board controller had to interpret each press and then encode and send that data to the computer for processing. Historically, that’s always meant a limit on the number of keys that can be reliably understood by the keyboard, and to a degree, that’s still true. Because of that, none of these boards will be perfect.
Razer advertises 10-key rollover in gaming mode, and we still don’t understand why it can’t just be active all the time. Meanwhile, Logitech’s website claims a 26-key rollover on the G710+, and Gigabyte says that their controller can handle up to 64 independent keys simultaneously. While ludicrous, these numbers are still easily testable, something that can’t necessarily be said of mice. However, since the average person only has 10 digits to use for typing, we did have to call in a few friends to help.
Since these are mechanical keyboards, no preference was given to assumed rows or columns of keys. Instead, we press one standard key, followed by a modifier (Shift, Ctrl, Alt), repeating that process until we hit the alleged limit of each board, and then randomly release each key to ensure that the order was being accurately reported.
Each keyboard performs about as well as its advertised figured indicates, but in the cases of Razer and Logitech, their numbers are a fair bit better than was expected.
Despite the admirable performance of each board, the stand-out here is the Osmium. At 60 keys depressed simultaneously, even a full-sized computer keyboard starts to get crowded, especially when you consider all the people standing around it. For the last few, we tossed on some small objects to hold them down.
The nature of the test alone should prove just how silly these numbers are. At the most extreme, an average player might have a friend playing on the same keyboard, and so maybe 20 keys would be necessary, but anything beyond that is largely just for bragging rights.
Really talented typists can hit over 100 words per minute and at around five characters per word, that amounts to more than eight keys per second. Ignoring the time it takes to activate the keys or even the pause between presses, no one will ever need 64- or even 28-key rollover. At one point, USB controllers had problems handling more than 6 keys, but our tests show that this simply isn’t true anymore. For all intents and purposes, the Logitech and Gigabyte boards have N-key rollover, and unless you regularly find yourself with an extra few dozen fingers, none of these three boards are limited by anything more than your own reaction time.