# USB-A vs USB-C speed differences



## rougue (Mar 29, 2021)

Could somebody who understands these things please interpret the differences here? 
Same devices, same Macbook M1. An 8TB SSD in a UGreen 6Gbps USB-C enclosure.

1) USB-A cable -- plugged into a *10Gbps port on an Anker hub.*









2) USB-C cable -- plugged *direct* (into the Macbook M1 "USB4" port).







I had very similar results testing it with a different SSD using the same devices.


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## jaketanner (Mar 29, 2021)

Not sure, but this might help. https://www.tomshardware.com/news/usb-4-faq,38766.html

Could just be the device or the cable.


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## Summa (Mar 29, 2021)

Afaik is USB-C just the connector, could be thunderbolt or display output as well and USB type/speed isn't guaranteed.


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## colony nofi (Mar 31, 2021)

Yes. USB A, B and C (and their mini / various counterparts) are JUST connectors.
USB 1, 2, 3, 4 (and the variants... 3.1, 3.1 Gen 2 etc etc) describes the data transport and its associated maximum speed. You can run USB 2 over USB C, or USB 3.1 or USB 4 even. 

There's many posts on it around online - this one isn't too bad / is nice and clear






The difference between USB-C and USB 3.0 ports


Alogic




www.alogic.co





Now, there's more complications when running different things over USB. There's various data latencies to worry about, as well as driver layers. 

And the thing you are connecting to the data transport might be the bottle neck itself.

OR the use of that data in software.

For instance - for us VI users - lets look at kontakt.

Lets put a sample library on an m.2 NVME drive in a USB 3.0 enclosure running over USB C.

The drive can do say 2500MB/s reads according to a tool like blackmagic disk speed checker.
BUT - kontakt reads and writes smaller amounts than blackmagic tests. So - we need to look at the drives max reads for 128k chuncks (its a little less than this, but will do for this demonstration)

That might be say 800MB/s max.

Now, USB 3.0 runs at 4800 mb/s (mega BIT) so thats 600mB/s) - which means it IS holding back the drive, but only by a little bit. USB 3.1 at 10mbit/s has more than enough bandwidth for this drive for this use.

But then we look a little closer again - and we note that kontakt itself cannot read/write at 600mB/s. Indeed, closer inspection shows it maxes out around 250mB/s, and often its between 100-200mB/s.

So - in this case, you will not notice that the USB 3.0 connection is slightly slowing your drive, as the software cannot keep up.

It also means that in many circumstances, a SATA 3 drive (max bandwidth of 6000mb/s) will do very nicely with only a USB 3.0 connection (max bandwidth of 5000mb/sl) - and you won't notice the small bottleneck. And USB 3.1 will be more than enough. 

Now - I believe your 870QVO is a SATA3 SSD. That has a MAXIMUM throughput of 600MB/s. So no matter what transport you are using, the ABSOLUTE maximum will be 600MB/s. Most SATA 3 drives top out at 550 or so, with many in the 400-550 area. Yours is in that space. It might be a little bit below what one might expect.... but its not bad.

I happen to have 2 of these 4TB QVO drives sitting in a blackmagic dock - connected via USB 3.0.
They max out around 350MB/s. This is less than the USB 3.0 spec, but to be expected really. There's always inefficiencies in the system. And I'm not needing them to be MEGA fast. Just fast enough. 








Now, in practice, there's many reasons why you might want the higher bandwidth - you don't just run kontakt instruments for example. Then, running a faster protocol (say thunderbolt3, which gives you 40000mb/s bandwidth) may prove useful. But its important to figure out what you NEED, and get your head around the idea of data throughput and where bottlenecks arrise.


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## Al Maurice (Mar 31, 2021)

Actually it depends on the device behind the connector not just the bus, which is why you can get a peripheral that can use various connectors. The bus and your PC/Mac just sets the limit if you like. Moreover I would also check the format of your drive, some are capable of better throughputs too. Although different apps and plugins can handle one format better over another, as has been stated above.


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## jcrosby (Mar 31, 2021)

Colony pretty much said all there is to say.... Not only are the connectors just the connection type, you want to spec your cables before buying them... i.e. 3.0 vs 3.1; and always check if a USB C cable supports thunderbolt, as the average one doesn't. The same goes for hubs, adapters etc.

The only thing I'll add is USB cables tend to be grossly misrepresented when it comes to generic cables. Amazon has tons of reviews of people purchasing cables as advertised as 3.1 but they turn out to be 3.0. And proper thunderbolt 3 cables are pricy, starting around $50-ish and going way up from there. (At least last time I checked... They may have gone up or come down a few bucks since then). The point is don't expect 40 Gbps from a generic $10 cable). Once again, the same goes for adapters... Buy form a place that has a reputation for accurate specs...

Short version, spend a little more and buy cables/adapters you know are specced correctly. But don't pay apple's tax either... Apple are selling you aftermarket cables at a premium price... Granted you get what's advertised, but you get gouged in the process. Monoprice is a solid alternative. Great prices while always being specced accurately. They even make solid audio cables 





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Monoprice, Inc. (DBA. MonoPrice.com) specializes in the wholesale distribution of world class cable assemblies for home theater, PC, and high technology industries. MonoPrice.com offers a wide range of products from standard PC products, network cables, and HDMI cables to custom cable assemblies...



www.monoprice.com


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## Shad0wLandsUK (Mar 31, 2021)

colony nofi said:


> USB 3.1 at 10mbit/s has more than enough bandwidth for this drive for this use.


I think you mean 10gbit/s here right?
And as I recall there are two gens for 3.1 as well, which I believe have differing speeds


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## colony nofi (Mar 31, 2021)

Shad0wLandsUK said:


> I think you mean 10gbit/s here right?
> And as I recall there are two gens for 3.1 as well, which I believe have differing speeds


YES! . Sorry - was tired after a long day of mixing. 
There are two different gens for 3.1. There are even rebrands by usb, where one thing becomes another. I just look it up every time I need to know. 

@Al Maurice makes a good point - in that the implementation of your peripheral can also be a bottleneck. I'm seeing it less and less these days, but on lower cost (consumer level) devices, I'm sure it is still a problem. I'm guessing (*without having done the tests myself*) that most thunderbolt devices wouldn't have this problem - because of the nature of what thunderbolt is (an extension of the PCIE interface outside of your computer box). 

(Thunderbolt gets confusing too though - as you can run different protocols over a thunderbolt port. If something is natively thunderbolt, it will include the thunderbolt symbol both on the device, and on the cable)


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## Shad0wLandsUK (Apr 1, 2021)

colony nofi said:


> YES! . Sorry - was tired after a long day of mixing.


Understood


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## rougue (Apr 2, 2021)

My recent thread actually shows that USB3.1gen2 {10Gbps} loads Kontakt libraries a lot faster than USB3.1gen1 {5-6Gbps} or USB3.0.

14 seconds as opposed to 34 seconds for a 24GB library. (Although this is just one library so doesn't represent all libraries).

So this external NVME [restricted to 10Gbps] loads the same 24GB library at the same speed as the 30+Gbps internal Macbook m1 NVME.

Streaming might be a different affair though.


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