Which is faster? Class 10 SD Card or USB3 Extenal HHD?

[Windows Central Question]

I have an HP Envy Pro All-in-One (core i7-6700 etc) that has a 256G SSD. It's a royal P.I.T.A. to get access to the disc to upgrade it. So I'm pretty much limited to external storage to expand capacity. The unit has a built in SD-card reader and USB3. Which would be faster for app/data loading - a UHS-II class SD-card (assuming the Realtek card reader/driver can support that standard) or an external USB-3/SATA-III SSD? Any guidance gratefully received.

 

[xandros9]

I would also take portability into account since I can leave an SD card in my computer but not quite an entire hard drive. Also depends on space required, SD cards are much more expensive per gigabyte than hard drives.

 

[pjhenry1216]

So, its difficult to give you an exact answer because there are some ambiguities in your question (such as USB3/SATAIII as a type of SSD). However, it's likely the SSD would perform faster assuming there are no given bottlenecks. USB3.0 (as opposed to 3.1 which is about double) can theoretically perform at 5Gbits/s (though real-world puts it around 3.2Gbits/s)... this translates to about 400 megabytes per second throughput. SD UHS-2 can achieve a theoretical maximum of 312 megabytes per second. So, you have a real-world expected throughput of 400 megabytes per second vs a *theoretical* throughput of 312 megabytes per second. So you're almost guaranteed to get faster speeds with USB3.0. In regards to SATAIII, I'm assuming you're referring to a SATAIII SSD with a USB3.0 bridge, in which case, you'll be bottlenecked at USB3.0 speeds. SATAIII is faster than USB3.1 which is faster than UHS-II. But consider any bottlenecks that may exist (UHS-II on an SD reader utilizing USB2.0...

Edit: I didn't take cost or portability into account. If you want to do so, see the post above.

 

[rcciren]

Many thanks for the guidance, peeps. I've popped a Sandisk Ultra Fit (150MB/s) USB3 mini memory stick in one of the SS-USB ports as this was the cheaper option versus SD-cards. 128Gb that that brings is more than enough for my OneDrive and CAD storage needs. I've just timed file opening some large plans within PlansXpress and can't detect any real difference in opening the CAD files from the SSD or the USB drive. Thanks again as your replies helped crystallise my thoughts.

 

[Rubidad]

So, its difficult to give you an exact answer because there are some ambiguities in your question (such as USB3/SATAIII as a type of SSD). However, it's likely the SSD would perform faster assuming there are no given bottlenecks. USB3.0 (as opposed to 3.1 which is about double) can theoretically perform at 5Gbits/s (though real-world puts it around 3.2Gbits/s)... this translates to about 400 megabytes per second throughput. SD UHS-2 can achieve a theoretical maximum of 312 megabytes per second. So, you have a real-world expected throughput of 400 megabytes per second vs a *theoretical* throughput of 312 megabytes per second. So you're almost guaranteed to get faster speeds with USB3.0. In regards to SATAIII, I'm assuming you're referring to a SATAIII SSD with a USB3.0 bridge, in which case, you'll be bottlenecked at USB3.0 speeds. SATAIII is faster than USB3.1 which is faster than UHS-II. But consider any bottlenecks that may exist (UHS-II on an SD reader utilizing USB2.0...

Edit: I didn't take cost or portability into account. If you want to do so, see the post above.

Greetings,
My new laptop has a USB 3.1 type C port. I've been thinking of getting a USB 3.0 external enclosure (3.1 ones are costly and hard to find). I would throw in a 500 GB SSD (probably a M.2 2280, again because of expense).
What kind of transfer speeds would I be looking at?
I assume the bottle neck will be the SSD. Am I correct?

 

[pjhenry1216]

Greetings,
My new laptop has a USB 3.1 type C port. I've been thinking of getting a USB 3.0 external enclosure (3.1 ones are costly and hard to find). I would throw in a 500 GB SSD (probably a M.2 2280, again because of expense).
What kind of transfer speeds would I be looking at?
I assume the bottle neck will be the SSD. Am I correct?

If you get an enclosure that takes an M.2 drive, my guess at the bottleneck would be the USB 3.0/enclosure. I say guess because I have no idea what M.2 2280 drive you want to use (as that's just the form factor) *but* there are various drives out there that can theoretically perform more than twice as fast as USB 3.0. Personally, if you're going to go with a USB 3.0 enclosure, you're probably better off getting a SATA enclosure along with a regular 2.5" sata ssd. Anything else will have you spending a large amount and probably not getting more performance. USB 3 can go to a theoretical maximum of 640 MBps. There are M.2s out there that can get ~3.5GB/s read speeds and ~2.1GB/s write speeds (granted, this is the high end). So, I'd stick with a 2.5" SATAIII SSD with a USB3.0 SATAIII enclosure. You can probably get slower M.2s, but honestly, if SATAIII is already close to saturating the USB3.0 throughput, what's the point?

 

[pjhenry1216]

As an addendum, if you're looking at a size of ~500GB, you may just look into bypassing the DIY route and looking for a 512GB USB flash drive. You may lose some speed, but honestly, you probably wouldn't be getting the maximum anyway. I mean, what kind of work are you doing to begin with? It may be a simpler solution (smaller & more portable, basically simpler to work with) if you don't absolutely need to eek out every bit of performance possible. Just remember, these devices are outpacing what most consumers really need nowadays. So just bear in mind what you want to do with it. I mean, if money isn't an issue i guess, then who cares? But at that point, get a laptop that meets your requirements instead. Or, maybe a laptop doesn't meet your requirements and you should use a desktop? Maybe remote from a cheaper laptop and work that way?