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Does plugging in a Mechanical k/b into USB 2.0 significantly slower than USB 3.0? - Page 2

post #11 of 16
Thread Starter 
Quote:
Originally Posted by mechtech View Post

Bandwidth has no relevance to a keyboard. A keyboard literally uses thousands of times less bandwidth than USB 1, even if you're mashing your hands on the keyboard.

Polling rate and protocol limitations are all that matters. In this respect, all USB will be identical, and PS2 will be superior (lower latency by a few milliseconds).

My Steelseries 7g has a PS/2 cable BUT my motherboard (asrock extreme7 gen3) has NO PS2 port on the back.

Thus, I must use the USB Adapter to connect to my PC. Does this "null" or "negate" the advantages of the PS/2 then???
post #12 of 16
Thread Starter 
Quote:
Originally Posted by FallenFaux View Post

There isn't a difference between USB 2 and 3 as far as keyboard performance goes. However, PS/2 would be faster and allow you full n key rollover (if your keyboard supports it.)

My CM Quick fire pro has a funtion key to allow for "FULL N " key rollover and it has a USB cord and is listed as "FULL USB 2.0 " on the website.

Is it stil possible to achieve FULL N KEY rollever on USB 2.0 then? or must it be via ps2?
post #13 of 16
Full n-key rollover is achievable through PS/2. Special tricks or designs are needed to do a high n-key rollover (not full) through USB (Sidewinder X4 for example). The increased rollover for the Quickfire Pro uses its own little tricks to achieve the ability but there are some reported compatibility problems, though I forget what specifically but it was what turned me away from owning one.
post #14 of 16
Quote:
Originally Posted by atomicmew View Post

There is physically no difference.

USB 3.0 achieves faster transfer rates by increasing the size of data (number of packets) per cycle, but a keyboard will not saturate 2.0 or 3.0 either way. So the speed will be determined by the polling rate which is the same in 2.0 and 3.0. There have been some threads on overclocking the polling rate, but I don't think it is worth the effort. Do the google if you're interested.

Other than that, if your keyboard is PS/2 compatible, use that instead. PS/2 doesn't have a polling rate and simply sends an interrupt signal to your CPU. More importantly though, PS/2 has true NKRO as each key has it's own signal, meaning you can literally press all the keys on the keyboard at the same time and have them all register. USB keyboards are generally plagued by 5 KRO and ghosting issues.

 

So, if I was to connect a USB keyboard into a USB hub, and then a USB hub into my USB port on my PC, would my keyboard become noticably slower, or would that make any difference at all?

post #15 of 16
Most likely not measureable. The few times I've connected my keyboard / mouse / n52te through the hub to test something I couldn't see a difference. That may change if you are saturating the usb speed though, not sure. Didn't try it while my usb hard drive was transferring full speed through the hub. Assuming you aren't saturating the bandwidth I would imagine at most a slowdown of 1 or 2% of a milllisecond worst case going though a hub. That is a guess though. Definitely not noticeable.

As I understand hubs the best way to look at them is like a simple manifold, or a 4+ in to 1 out. But in this case the pipe size is quite large. Devices use different bandwidth, usually very low so small pipes. I used to do plumbing so I look at a single USB 2.0 as say a 6" pipe. Keyboard / Mouse / Handpad or whatever might be a half inch pipe worth of data transmission, likely less. The slowdown there "might" be is the signal is travelling through an extra few inches of pipe, but the size is so big that it shouldn't matter. Talking percentages of a ms worst case in time. I think the only reason USB 2 and 3 came about is for webcams and hard drive stuff. Average input devices could run perfectly fine on usb 1.0 with no trouble, they just don't use that much bandwidth (or pipe size).
Edited by Tadaen Sylvermane - 5/12/13 at 9:10am
 
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Micromachine
(8 items)
 
 
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i7 4500u Inspiron 15 7000 Integrated 8gb 
Hard DriveOSMouse
120gb Samsung EVO SSD Debian Logitech m705 
CPUMotherboardRAMHard Drive
AMD 5350 Kabini AsRock AM1H-ITX 8gb Gskill Ripjaws (2x4) Samsung 120 Evo 
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WD 1tb 2.5 WD 2tb USB 3.0 Ubuntu Server 16.04 Antec ISK 
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post #16 of 16
Quote:
Originally Posted by Tadaen Sylvermane View Post

Most likely not measureable. The few times I've connected my keyboard / mouse / n52te through the hub to test something I couldn't see a difference. That may change if you are saturating the usb speed though, not sure. Didn't try it while my usb hard drive was transferring full speed through the hub. Assuming you aren't saturating the bandwidth I would imagine at most a slowdown of 1 or 2% of a milllisecond worst case going though a hub. That is a guess though. Definitely not noticeable.

As I understand hubs the best way to look at them is like a simple manifold, or a 4+ in to 1 out. But in this case the pipe size is quite large. Devices use different bandwidth, usually very low so small pipes. I used to do plumbing so I look at a single USB 2.0 as say a 6" pipe. Keyboard / Mouse / Handpad or whatever might be a half inch pipe worth of data transmission, maybe smaller. The slowdown there "might" be is the signal is travelling through an extra few inches of pipe, but the size is so big that it shouldn't matter. Talking percentages of a ms worst case in time.

 

Interesting. I just ordered a USB3 hub for my desk for organizational purposes, and because my cord for my Filco mechanical is very short, and I only thought about the polling frequencies/latency after I ordered it. 

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