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Can I use as many USB Port as possible?

by 1931poppy / September 23, 2006 10:09 AM PDT

i am using ALL 6 USB ports on my computer, so i bought a extension - which extended one of my ports to 4 - so now, i am using 9 ports.

However, i will need more space, for more - so if i was wondering is there a limit to how much a computer can have?
or will it have any technical problems? - like not being able to handle the amount of plug ins, or burning the hard drive out?

my computer is a new computer, with a dual core processor

i already have an external harddrive, webcam, bluetooth, control pad, RF receiver, printer, and i use the extra two for digi cams and USB stick memory - - and i would like to add another external harddrive!!

so would it hav any problems?!?

Thanks for reading, and thank you more for helping!!

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by Darton Fury / September 23, 2006 10:45 AM PDT

supports a maximum of 127 peripheral devices per computer when properly chained with USB hubs.

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by albizzia / October 6, 2006 4:51 PM PDT
In reply to: USB

Up to 127 USB devices - but remember that each hub also counts as a "device". If that isn't enough, you could add an additional USB port card, but I doubt that will be necessary.

Connect your "highest speed" devices (hard drives, flash drives, webcams) on a short path (no hubs, if possible) leaving your slower devices (mice, modems, graphics tablets, printers) connected through 1 or more hubs.

Some devices draw their power from the USB port, in those cases make sure they are on a "primary port" or powered hub. Devices that have their own power supply will work fine on an unpowered hub.

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USB Port Limits
by Grif Thomas Forum moderator / September 23, 2006 10:52 AM PDT

The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer. Unfortunately, the more you connect, the more possibility there is to have issues.. If you're using XP, then there shouldn't be a problem but I try to limit USB devices to the fewist number I can.. I also use "powered" USB hubs to prevent some of those issues.

In addition, check the hard drive instructions. Some hard drives need to be connected directly to the USB port on the computer..

Hope this helps.


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Is the Computer's Power Supply One of the Issues....
by tobeach / September 24, 2006 3:22 PM PDT
In reply to: USB Port Limits

you referred to, Grif? Any rule of thumb on say 450 watt? If you use a "powered" hub to get past this (PS) issue, are any special drivers required above & beyond those supplied w/ XP & used for the built ins? Curious... Thanks in Advance. Grin

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There are no special drivers that are required for
by retired / September 24, 2006 10:25 PM PDT

a powered USB hub using XP.

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'Retired' Is Right..
by Grif Thomas Forum moderator / September 25, 2006 8:33 AM PDT

The Power Supply isn't a problem and there are no special drivers for XP. Only some types of devices required the powered hub, (things like printers and external HD's usually work better with one) but it's not really a drain on the over-all power supply.

Hope this helps.


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(NT) (NT) Thank you BOTH for Your Useful Replies!! :D
by tobeach / September 25, 2006 4:05 PM PDT
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I use for a long time USB Powered Hub
by FrenchyHey / October 6, 2006 10:28 AM PDT

Many problems come from the power that some of the hardware we use on USB, a good example a Web Cam connected directly to your USB Root instead of the USB Powered Hub and Add a scanner connected to the computer and most of the time it just too much, but put them on a USB Hub with Self Powered and bingo problems resolved.

My mothers in law could not connect on her computer the scanner and Digital Camera at same time and have to go at the back of the computer, with the USB powered hub problems was resolved right away and no more digging behind the computer.

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A different route
by rje49 / October 7, 2006 12:26 AM PDT

I've had problems using USB hubs, even powered ones, mostly with higher-power type applications where it simply fails work. So instead, I added a 5-port USB 2.0 PCI card; a $25 Wal-Mart special. A neater set-up, and I've had absolutely no problems and no need for any hub - sold it on Ebay. If you have the open slot, it's a better way to go for sure.

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127 DEVICES????
by ericj9 / March 9, 2007 3:31 AM PST

Once upon a time, I took an A+ class (got a B+ in it...) and I remember hearing a fairy tale about USB having the capability of supporting 127 devices. I seriously don't know where this story came from because reality comes crushing down when you start to approach double digits. Ten devices seems like alot but you have a right to have anything you can support on your system.

I don't know what the REAL answer is but, definitively, 127 is pure BS! Regardless of whether you are using a powered hub, dual power cables (usb cable that splits into two ports one provides extra power, the other data and power), PCMCIA card--whatever, it appears that a computer can support maybe twice as many devices as you have internal ports. In other words, if you have a laptop with:
- 2 integral USB 2.0 ports
- two 7 port powered USB hubs
- PCMCIA USB card with 4 ports and a power cord to the card
- unpowered USB hub with 4 ports
- one serious power strip (use a Power Squid all others are designed very poorly) to support 20 devices with their own power supplies

You are looking at supporting 4 devices...nice huh?!! ~>:(

This isn't hard and fast. It really can vary especially based on the amount of power being drawn and the resources being used. Another factor not mentioned either is that the CPU/RAM may not support too many devices either. This should be a non-issue with a duo core but straight talk is few and far between on this topic. I don't have the energy to check out the RFC on the subject since I've seen too many examples of USB fluff in the past.

Short answer: as long as your hub (extention) has power, and your storage devices are directly used in one of the original 6 ports you SHOULD be okay. I believe you have an upper limit of twelve single port devices on your system. It might vary thoug. If you want to be sure another PCI card should help. I wish I can give you a more definitive answer but I don't think ANYONE can give you a better one...not even the original USB engineers apparently...

May you and your system live happily ever after.

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Maybe an A+ had you studied more...
by Edward ODaniel / March 9, 2007 5:08 AM PST
In reply to: 127 DEVICES????

You are more than welcome to rectify your limited knowledge of
USB standards by following this link and doing a bit of studying (or at least reading).

The Universal Serial Bus Revision 2.0 specification Acrobat file should prove particularly illuminating.

After downloading unzip and start with the 5.6 meg USB_20.pdf and on page 13 do note (under Feature List):

Wide range of workloads and applications
? Suitable for device bandwidths ranging from a few kb/s to several hundred Mb/s
? Supports isochronous as well as asynchronous transfer types over the same set of wires
? Supports concurrent operation of many devices (multiple connections)
? Supports up to 127 physical devices
? Supports transfer of multiple data and message streams between the host and devices
? Allows compound devices (i.e., peripherals composed of many functions)
? Lower protocol overhead, resulting in high bus utilization

Your opinion of number of supported devices is fine but should be stated as such rather than attempting to insinuate that 127 devices is an inaccurate number ("but, definitively, 127 is pure BS!"). The "BS" was yours.

Do note further that the documentation later goes into greater detail especially regarding multuiple USB host controllers, mixing and matching, topology (provides clues about why some configurations work fine and others seem problematic or limiting [an answer to your personal "experiences"], device addressing (integer range 0 to 127), and most anything else you need to answer why.

Read, learn, enjoy!

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USB Beverage Cooler
by j1webb / April 10, 2007 8:56 PM PDT

I am thinking about rigging up an internal cooler to my computer by plugging in a USB Beverage cooler and then putting a fan on top of it. Then I intend on laying that on the inside bottom of my case so it will blow cooled air around inside my computer case.

However, I am concerned that the usb beverage cooler might draw too much current or somehow mess up my computer.

Do you have any thoughts or suggestions on this?

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