[mk1james]

Hi i,m thinking of buying a 3.0 USB as i want it for my 1TB hard drive which takes ages uploading large files, i was wondering if i got a USB 3.0 in my computer would it make it faster or would it be the same speed as i bought the PHD when there was only USB 2.0?

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The USB 3.0 interface will increase transfer speeds if the USB 2.0 interface is the bottleneck, and it might be.

What is the brand name and model number of your external 1TB HDD?

[DaffyKantReed]

The USB 3.0 interface will increase transfer speeds if the USB 2.0 interface is the bottleneck, and it might be.

What is the brand name and model number of your external 1TB HDD?

[Digerati]

The USB 3.0 interface will increase transfer speeds if the USB 2.0 interface is the bottleneck, and it might be.

No, sorry. That is incorrect. The USB 3.0 interface will only give you 3.0 speeds with 3.0 devices. It is backwards compatible so if buying new anything USB, I would get 3.0 to ensure best performance into the future.

[DaffyKantReed]

I don't quite understand, Digerati. If the OP has something like the Buffalo HD-HXU3, which is USB 3.0 capable, connected to a USB 2.0 port, then the interface is the bottleneck, no?

A USB 2.0 capable device would be no faster on a USB 3.0 interface, but it will work, as would a USB 1.1 device, correct?

[Neil Jones]

I don't quite understand, Digerati. If the OP has something like the Buffalo HD-HXU3, which is USB 3.0 capable, connected to a USB 2.0 port, then the interface is the bottleneck, no?

All throughput speeds are theoretical maximums.
USB 2 has a theoretical throughput of 480Mbit/s which is shared amongst all the devices. Ideally you'd get a transfer speed of about 60Mb/s under best conditions, but you'll be hard pushed to reach it sometimes.

USB 3 is theoretically as fast as a Firewire connection, 400Mb/s. However whether you reach it in practice is another matter.

With regards to a USB external hard drive, the ultimate bottleneck will usually be the speed of the hard drive. The majority of mechanical drives do not achieve throughput speeds on their own that come anywhere near close enough to break the SATA I speed test, never mind any other interface. USB is a lot slower bus. In theory the situation should be better with USB 3 devices.

[Digerati]

I don't quite understand, Digerati. If the OP has something like the Buffalo HD-HXU3, which is USB 3.0 capable, connected to a USB 2.0 port, then the interface is the bottleneck, no?

That is correct. But you said,

The USB 3.0 interface will increase transfer speeds if the USB 2.0 interface is the bottleneck

And that is incorrect - unless I am missing what you are saying.

The point is, you will only achieve 3.0 speeds if there are 3.0 devices on each end. 3.0 will not speed up a 2.0 interface or connection. 3.0 will toggle down to 2.0 speeds.

[SpywareDr]

I think what he's driving at is something along the lines of, if you hook up a USB 3-1/2" 1.44MB floppy drive to a USB 3.0 port it cannot not transfer data any faster than the floppy drive itself will allow. Even a USB 1.0 port is three times faster than a floppy drive.

1.44MB Floppy = 500 Kbits/s or 500,000 bits per second
USB 1.0 = 1.5Mbits/s or 1,500,000 bits per second
USB 1.1 = 12Mbits/s or 12,000,000 bits per second
USB 2.0 = 480 Mbit/s or 480,000,000 bits per second
USB 3.0 = 4.8 Gbit/s or 4,800,000,000 bits per second

Now think of it in reverse. If you have a device that is capable of transferring data at say 1,000 Mbits/s but you currently have it connected to a USB 2.0 port, the bottleneck is the 480Mbit/s USB 2.0 port. Hook it up to a USB 3.0 port and it should now be able to do the 1,000 Mbits/s.

Edited by SpywareDr, 28 April 2010 - 06:59 AM.

[DaffyKantReed]

Since the OP was asking about USB 3.0, I assumed his current motherboard has USB 2.0 capability. I asked the brand name and model number of the external 1TB HDD to check the specs and see where the bottleneck, if any, exists.

I should have also requested the brand name and model number of the external enclosure as it appears quite a few (13 from Newegg) have an external USB 3.0 interface.

Thanks for the clarification Digerati.

[Digerati]

Since the OP was asking about USB 3.0, I assumed his current motherboard has USB 2.0 capability.

Well, you are probably right, though he said,

i was wondering if i got a USB 3.0 in my computer

I was going on the computer currently supported 3.0, or he was considering adding a USB3.0 PCIe card. In any event, it really does not matter from which direction the communication flows, in a mixed circuit, 2.0 will be a bottleneck. Now whether that amounts to anything perceptible, I don't know.

Personally, my biggest hope with 3.0 is to FINALLY have a robust, hot-swappable, "universal" I/O method - something promised with 1.0 and never realized. Promised again with 2.0, but again not realized. And now, after many years, promised again with 3.0. Let's hope 3 times a charm.