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Windows 7: USB 3.0 Cards

03 Sep 2010   #1
Megaman0

Windows 7 64bit
 
 
USB 3.0 Cards

What is the difference between USB 3.0 cards with power supply connectors, and those without? When would you need a card with a power supply connector and when would you need one without? Does either or have a speed difference even though they both claim 5gbps?

Why don't they point these difference out when selling the product? As many boxes as I have seen, not once have they mentioned the difference or plus side/lack performance to either one.

Thanks!


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03 Sep 2010   #2
alphanumeric
Microsoft MVP

Windows 10 Education 64 bit
 
 

Are you sure that it's a power supply connector and not just another USB port? I've seen some with an "Internal" USB port or header on them. Can't say as I've seen one with a power connector on them.
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03 Sep 2010   #3
strollin

W7 Ult desktop, W10 laptop, W10 laptop, W8.1 tablet
 
 

USB 3.0 provides more power to connected devices than USB 2.0 did so the power connector is provided to allow for that extra power instead of relying on the bus to provide the extra power. USB 2.0 provided a max of 500ma to all connected devices whereas USB 3.0 provides up to 900ma total.
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03 Sep 2010   #4
alphanumeric
Microsoft MVP

Windows 10 Education 64 bit
 
 

Based on what Strollin posted, I would say the ones with the extra power connector have more ports than the ones that don't. The ones with lots of USB ports can't get enough power from the motherboard connector to power all the ports so they need an extra power connector. I would think there will not be any performance (speed) difference in the two cards, one just has more ports than the other and needs a little more juice to meet the 900ma per port spec.
My System SpecsSystem Spec
03 Sep 2010   #5
strollin

W7 Ult desktop, W10 laptop, W10 laptop, W8.1 tablet
 
 

Quote   Quote: Originally Posted by alphanumeric View Post
Based on what Strollin posted, I would say the ones with the extra power connector have more ports than the ones that don't. The ones with lots of USB ports can't get enough power from the motherboard connector to power all the ports so they need an extra power connector. I would think there will not be any performance (speed) difference in the two cards, one just has more ports than the other and needs a little more juice to meet the 900ma per port spec.
It's 900ma TOTAL, not per port. My guess is that the less expensive cards won't provide the connector and will rely on whatever power can be gleaned from the bus while the higher quality cards provide the connector to ensure the card can provide the power the 3.0 spec calls for.
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03 Sep 2010   #6
alphanumeric
Microsoft MVP

Windows 10 Education 64 bit
 
 

Actually I think it is per port?

A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0, which was raised to 6 (900 mA) in USB 3.0.
Universal Serial Bus - Wikipedia, the free encyclopedia
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03 Sep 2010   #7
Megaman0

Windows 7 64bit
 
 

Both of the cards only have 2 USB 3.0 ports. Some have an extra power connector while some don't. I hate technology sometimes.... You try to get USB 3.0 speed and you don't really get it because companies decide to make all different types of confusing elements in these cards!
My System SpecsSystem Spec
03 Sep 2010   #8
alphanumeric
Microsoft MVP

Windows 10 Education 64 bit
 
 

Having or not having an extra power connector shouldn't affect the speed. If it's advertised as being USB 3.0 and has the logo it should operate at USB 3 speeds.
My System SpecsSystem Spec
03 Sep 2010   #9
strollin

W7 Ult desktop, W10 laptop, W10 laptop, W8.1 tablet
 
 

Quote   Quote: Originally Posted by alphanumeric View Post
Actually I think it is per port?

A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0, which was raised to 6 (900 mA) in USB 3.0.
Universal Serial Bus - Wikipedia, the free encyclopedia
You're right, I misread it. The total current is limited to 5A in USB 3.0.
My System SpecsSystem Spec
07 Sep 2010   #10
Megaman0

Windows 7 64bit
 
 

Thanks guys. You've been awesome.
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 USB 3.0 Cards




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