USB 2.0 vs 3.0

[ZeeOSix]

The new Dell computer I ordered has both 2.0 and 3.0 USB ports. What's the difference?

I assuming you can't plug in a 2.0 USB device into a 3.0 USB port, or plug in a 3.0 USB device into a 2.0 USB port? Are the actual physical configuration of the ports different? They seem to be marked differently on the computer.

 

[Quattro Pete]

3.0 is significantly faster. Makes a big difference when you use it with external storage.

You can plug in a 2.0 device into a 3.0 port.
You can plug in a 3.0 device into a 2.0 port.

 

[Rick in PA]

I'm no expert, but I bought a portable drive that featured USB3 because it specified it would work on USB2.

The USB3 connectors have a blue insulating insert. The USB3 cables are usually blue. All for identification.

The USB3-A connectors (at the computer end) are the same size and shape as USB2-A connector but have an extra set of contacts, these extra contacts do not "make" if a USB2 connector is used. So you can use the USB3 port on the computer for either USB2 or USB3.

On the accessory, such as a portable drive, an extra connector is siamesed next to the USB2 connection. This extra connection provides the USB3 connectivity. On a USB3 accessory, you can plug in an older USB2 cable (I've tried it) and it will work, but at USB2 speeds.

In a nutshell, they made them compatible (except a USB3 cable can't plug into a USB2 accessory such as a portable drive, but that's not a problem). In order to take advantage of USB3, both devices have to offer USB3 and you have to use a USB3 cable (and that only makes sense).

Google USB3 images and it should make sense.
Also, Wikipedia has a good article: http://en.wikipedia.org/wiki/Usb3

 

[Errtt]

My recent bought laptop has ssd and I'm happy with the speed.
It has 3.0usb so I recently bought a Patriot Rage 3.0 flash drive and its a lot faster than the all the 2.0 flash drives I have.
I noticed the read/write speed of the drive compared to others I looked at was up there.
Someone once told me basically 3.0 is 10x faster than 2.0. Well I say its faster, but I'm also using a faster flash drive now too.

 

[Quattro Pete]

Originally Posted By: Errtt
Someone once told me basically 3.0 is 10x faster than 2.0. Well I say its faster, but I'm also using a faster flash drive now too.

Realistically, in my experience it's about 4x faster. When comparing transfer speeds, 2.0 maxes out at around 25-30 MB/s. 3.0 is around 100 MB/s.

 

[Rand]

From testing with external usb hdd.
2.0 will max around 37MB/s - Max sustained read
3.0 will max at whatever the drive is limited to.
I have a 2.5" samsung ext 1tb drive and it will get around 100MB/s



some usb 3.0 flash drives will still benefit on usb 2.0 by maxing them out.. there are also many slow usb 3.0 flash drives that dont even max out usb 2.0

 

[Donald]

in 2011 I bought an HP laptop and went out of my way to get one with eSATA. Then got an external harddrive with RAID 1 and SATA harddrives.

I was really hoping eSATA would take off, but it seems USB3 is the winner here.

 

[Nick R]

USB 3.0 and 2.0 are forward/backward compatible.

If you...
Use a USB 3.0 storage device on a USB 3.0 port it will run at full USB 3.0 speeds (>200MB/s)

Use a USB 3.0 Storage Device on a USB 2.0 port it will function at USB 2.0 speeds (~35MB/s)

Use a USB 2.0 device in a USB 3.0 or 2.0 port, it will function at standard USB 2.0 speeds.

I generally recommend only plugging keyboards/mice into USB 2.0 ports though, as some motherboards don't initialize the USB 3.0 controller fast enough to be used to enter the BIOS.

The compatability only extends to the port on the computer though. Mini and type B plugs are different between 2.0 and 3.0, so the cable for a USB 2.0 device will not fit one designed for a 3.0 port, and vice versa. But you can plug it into either port on the computer itself with no adverse affects.

2.0 devices will function at 2.0 speeds in either 2.0 or 3.0 ports.

3.0 will function as 2.0 devices in a 2.0 port, and at 3.0 speeds in a 3.0 port.

USB 3.0 is what you want to use if you have a compatible external storage device, as the read/write speeds are much much faster than 2.0. 2.0 tops out aroun 30-35MB/s depending on the controller on the motherboard, whereas 3.0 will top out around 200MB/s or faster.

 

[Quattro Pete]

Originally Posted By: Nick R
whereas 3.0 will top out around 200MB/s or faster.

Have you been able to actually find an external storage device that can sustain 200 MB/s? I'm still looking...

 

[Nick R]

Originally Posted By: Quattro Pete
Originally Posted By: Nick R
whereas 3.0 will top out around 200MB/s or faster.

Have you been able to actually find an external storage device that can sustain 200 MB/s? I'm still looking...


I've seen tests using SSDs in an external enclosure. Most hard drives will top out anywhere from 110 to 180MB/s

Some usb 3.0 flash drives are capable of near that as well. I have a mushkin one that will do 170MB/s. That also means if b you have.multiple external hard drives connected to the bus you won't be severely limited. You can sustain pretty much full speed on two drives connected to the same 3.0 bus or hub.

 

[Errtt]

I want to say my flash drive advertise just under 200 MB/s when I bought it but I have thrown the packaging away. I have been known to be wrong before and the ol lady still reminds me often

 

[Quattro Pete]

One should also consider that the bottleneck may be your own internal HDD when copying to/from an external drive that's advertized at 200 MB/s.

I have a fairly new laptop, but no SSD. The internal HDD maxes out at around 100 MB/s.