Low latency Keyboards

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Samhain
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Low latency Keyboards

Post by Samhain » 05 Jan 2014, 19:12

Since there is a low latency mouse thread, I thought I would start one on keyboards. I am so fascinated by low latency lately, that I went out and bought a nice Razer mouse, followed all the guides on this forum and wow! Big difference especially with VSYNC OFF.

Now I start reading about keyboards and I had no idea that legacy PS/2 is superior to USB specifically for keyboards. Apparently USB polls at a specific rate waiting for your input (key press). With PS/2, there is no polling. Each and every key press is registered first in/first out as fast as you can humanly type. There are other benefits too (like being able to register several keys at the same time and less CPU load since there is no polling).

I have ordered a Filco keyboard with Cherry MX black mechanical switches (these are apparently the gamer friendly switches) and I will be using PS/2. Its funny because I have been historically against keeping legacy ports on system boards. Now I am happy my Z87 has a PS/2 port still! :)

Anyone else have thoughts on low latency keyboard tech?

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nimbulan
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Re: Low latency Keyboards

Post by nimbulan » 05 Jan 2014, 19:39

I am using a Rosewill MX Brown board on PS/2 myself. I would not recommend Rosewill to others however since they are known to have flaky USB ports but I know I am careful enough to avoid breaking it. My previous membrane keyboard was PS/2 as well and now that I think about it, I don't think I've ever had a USB keyboard on one of my computers so I couldn't say how much of an improvement PS/2 provides. The one thing I do notice, however, is the N-key rollover. Being able to press every key on the board at the same time and have them all register properly is amazing and something I could not live without now. This feature is available on some USB keyboards now, and most USB mechanical keyboards will support at least 6-key rollover.

One thing that has surprised me is that one of my friends has a high end gaming motherboard designed for tri- and quad-SLI yet has no PS/2 ports. A very odd decision from eVGA.

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Chickenfeed
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Re: Low latency Keyboards

Post by Chickenfeed » 05 Jan 2014, 23:42

Ive been using mech boards via PS/2 for a few years now. Basically PS/2 is interupt based where as USB uses polling. The biggest difference though is the ability for PS/2 to accept full key rollover on supported board matrixs (basically any mech board will have full N key rollover, a few dont still however) This just means there is no limit to the number and location of depressed switchs, you could be using all 10 fingers and the system will register all of your requested input (hell you can even cover as much of the board as possible and register the whole thing at once if you had to)

Cheaper USB based boards dont have gaming optimized key matrixs so you may run into issues depressing as few as 3 keys at once. Now days for average WASD configs any gaming focused USB board will have an optimzed matrix so this wont be problem for most users. If you venture into alot of custom keybindings however issues may arrive ( ive seen complaints from those whom run emulators and tend to use thr righter most side of a board)

Switch type is another preference as well. On balance i like my current brown switched board but ive used both black and blue boards as well. Brown is closer to a middle ground of the two where blues are nicer for general typing and blacks for gaming (if you are used to standard scissor or membrane switched boards youll find blacks fatiguing after awhile until you get used to it)

Mech boards have grown substantially in popularity and availability in the last few years so its become easier and cheaper to get one of your liking (as little as 5 years back you'd often need to import one from Asia)

Im a fairly competent typist (80 WPM) and even went as far as buying a board for use at my place of work. Id rather not be subjected to a membrane board if i dont have to be :)
Cool thing about about that when i started there i noticed all the POS terminals had IMB buckling spring boards, there were even some extras still sealed brand new! I thought that was pretty sweet (people still buy those boards on ebay in droves)

(This post brought to you by a 5" touch screen... the irony)
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Black Octagon
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Re: Low latency Keyboards

Post by Black Octagon » 06 Jan 2014, 15:12

I love my mechanical (USB) keyboard but am slightly confused by the enthusiasm in this thread.

1) How much latency does one actually lose by abandoning polling/USB for PS/2? Is it really in the 'noticeable' range?

2) What is the advantage to being able to register so many key depressions at once? I've never had the need for anything more than Ctrl-Alt-Del.

Don't mean to come off as dismissive, truly. I'm just trying to learn. Cheers

Sent from dumbphone (pls excuse typos and dumbness)

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nimbulan
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Re: Low latency Keyboards

Post by nimbulan » 06 Jan 2014, 17:11

Black Octagon wrote:2) What is the advantage to being able to register so many key depressions at once? I've never had the need for anything more than Ctrl-Alt-Del.
It is definitely helpful for games. Performing multiple actions at once can often lead to missed key presses (such as crouch+forward+sidestep+additional action.) Newer gaming keyboards have optimized matrices to prevent this from happening near the standard WASD controls, but it can still happen especially if you use non-standard control schemes.

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sharknice
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Re: Low latency Keyboards

Post by sharknice » 06 Jan 2014, 18:05

A lot of new gaming keyboards support 1000hz polling. For example the new mechanical Corsair keyboards all have hardware switches that allow you to switch between 1000, 500, 250, and 125hz.
I had a Corsair K90 and switched to a K95 when it came out. They both support N-key rollover.

I don't think I really noticed much difference going form 125hz to 1000hz for the keyboard. It probably isn't as important as it is with mice.

I definitely noticed the N-Key rollover difference though.
In gaming if you're pressing a lot of keys at once, strafing diagonally while switching weapons and jumping for example is 4 keys, add crouching and that is 5 keys. A lot of keyboards won't register all the keys.
I type well over 100 wpm and on keyboards with low rollover I will sometimes get random typos which I believe is because the keys aren't depressing fast enough and are hitting those specific combinations that won't register simultaneously. It could just be because the membrane keys don't work as well though.

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Chief Blur Buster
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Re: Low latency Keyboards

Post by Chief Blur Buster » 06 Jan 2014, 18:10

sharknice wrote:I definitely noticed the N-Key rollover difference though.
In gaming if you're pressing a lot of keys at once, strafing diagonally while switching weapons and jumping for example is 4 keys, add crouching and that is 5 keys. A lot of keyboards won't register all the keys.
Very interesting, I wasn't aware of this real-life scenario requiring 5-key rollover! I don't have the competitive capability to do that.
sharknice wrote:I type well over 100 wpm and on keyboards with low rollover I will sometimes get random typos which I believe is because the keys aren't depressing fast enough and are hitting those specific combinations that won't register simultaneously. It could just be because the membrane keys don't work as well though.
Same.

Once, I benchmarked 142 WPM on an online typing test (710 keypresses per minute, no uncorrected errors). It slows down to 100-120 WPM for paraphrasing randomly ordered words.
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sharknice
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Re: Low latency Keyboards

Post by sharknice » 06 Jan 2014, 18:25

Chief Blur Buster wrote:
sharknice wrote:I definitely noticed the N-Key rollover difference though.
In gaming if you're pressing a lot of keys at once, strafing diagonally while switching weapons and jumping for example is 4 keys, add crouching and that is 5 keys. A lot of keyboards won't register all the keys.
Very interesting, I wasn't aware of this real-life scenario requiring 5-key rollover! I don't have the competitive capability to do that.
sharknice wrote:I type well over 100 wpm and on keyboards with low rollover I will sometimes get random typos which I believe is because the keys aren't depressing fast enough and are hitting those specific combinations that won't register simultaneously. It could just be because the membrane keys don't work as well though.
Same.

Once, I benchmarked 142 WPM on an online typing test (710 keypresses per minute, no uncorrected errors). It slows down to 100-120 WPM for paraphrasing randomly ordered words.
Yeah it is strange that a lot of those sites just do randomly ordered words. When you learn how to type you first learn the muscle memory for letters, then you eventually learn words, then sometimes eventually phrases and whole sentences.

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Chickenfeed
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Re: Low latency Keyboards

Post by Chickenfeed » 07 Jan 2014, 22:30

In my WoW days I used alot of modifiers while playing to manage all the skills, as well as targeting, moving etc. It was quite easy for me to hit 5 or 6 keys at once :shock: It was what personally led me to getting my first board when I was younger because I was running into issues with limited roll over.
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dreamss
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Re: Low latency Keyboards

Post by dreamss » 07 Jan 2014, 23:36

i have a cherry ps2 here. ps2 is no polled so no latency

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