Speed of transfer

[Rufus]

I have a SanDisk Extreme Pro 32GB card and its label shows 95MB/s. I believe that is the read speed and the write speed is 90MB/s.

When I put the card in my PC's internal multi-card reader and copy the file to my PC, Windows explorer shows it is transferring files at a fairly consistent 18.5MB/s. I don't expect to achieve the headline claimed performance, but less than 20% of it seems a raw deal.

The PC has an Intel i7-7700K 4.2GHz CPU, and 32GB of RAM and is running Win10.

I cannot find the card reader spec in Windows, but visually it looks just like this one: https://www.overclockers.co.uk/akasa...cm-03n-ak.html

Which item do you think might be weakest link?

[Manfred M]

Your built in reader is likely the problem; they tend to be USB 2 compatible.

To reach those speeds you will need an external reader USB 3 reader and use a USB 3 port, assuming your computer has one. Most modern computers have a mix of USB 2 and 3 ports. If I accidentally plug my card reader into a USB 2 port on my laptop the downloads take forever. I throw it into a USB 3 and I get great speeds. Unfortunately, externally the USB 2 and USB 3 ports look identical, so you'll have to check your manual.

My desktop has plenty of USB 3 ports so I leave my Lexar USB 3.0 reader permanently plugged into the port. It just simplifies the whole download process.

The other change I made is that my desktop has a very fast M.2 SSD drive, so I download to it, rather than my slower main drive (which is a standard SSD) or the mechanical hard drives that I use for long-term storage.

[Rufus]

Your built in reader is likely the problem; they tend to be USB 2 compatible.

To reach those speeds you will need an external reader USB 3 reader and use a USB 3 port, assuming your computer has one. Most modern computers have a mix of USB 2 and 3 ports. If I accidentally plug my card reader into a USB 2 port on my laptop the downloads take forever. I throw it into a USB 3 and I get great speeds. Unfortunately, externally the USB 2 and USB 3 ports look identical, so you'll have to check your manual.

My desktop has plenty of USB 3 ports so I leave my Lexar USB 3.0 reader permanently plugged into the port. It just simplifies the whole download process.

The other change I made is that my desktop has a very fast M.2 SSD drive, so I download to it, rather than my slower main drive (which is a standard SSD) or the mechanical hard drives that I use for long-term storage.

Aha, I thought it might be the card reader, even though it has two blue USB3.0 ports (as well as four white USB 2.0 ports and an eSATA) built into it.

My configuration uses the SSD for Windows and programs and the HDD for all data. Everything that is already on the computer loads pretty quickly; it is just the download from the card that takes a noticable amount of time. If I tire of downloading at a sedate 40 images per minute I now know what to try. Thank you Manfred.

[rpcrowe]

When I shot with older Canon DSLR cameras (up to the 40D) which had smaller file sizes, I never noticed any difference in reading or writing to and from the cards despite the speed of the cards,

However from my 7D on, the card speed mattered in writing to and reading from the card. I would definitely notice the faster speed CF cards being more efficient.

When I shot with a pair of 7D cameras, I noticed a difference in the download speed of a fast UDMA card as opposed to earlier type cards.

[dje]

Hi David

I'm inclined to agree with Manfred on this. I think you would be well advised to buy an external SD card reader with USB-3 or USB-c interface. They are quite small and cheap these days. And plug it into a USB3 or USB-c port on the back of the computer ie one which directly interfaces to the motherboard (not just through the built in card reader panel). Just out of interest, I did a few quick tests using AJA Test software.

Sandisk Ultra 30MB's

Old USB2 card reader Read 19MB/s Write 10MB/s
New USB c card reader Read 40MB/s Write 12MB/s

Sandisk Extreme 90MB/s

Old USB-2 card reader Read 19MB/s Write 19MB/s
New USB-c card reader Read 91M/s Write 49MB/s

The results speak for themselves.

Dave

[george013]

In general an usb3 is partly blue inside. And a usb3 has 9 channels vs usb2 4 channels. It's not only the port that matters, also the used cable. So if you've a bag with usb cables, what will happen in time, you must be able to see the differences between usb2 and usb3.

George

[Rufus]

And plug it into a USB3 or USB-c port on the back of the computer ie one which directly interfaces to the motherboard (not just through the built in card reader panel).

Sandisk Extreme 90MB/s

Old USB-2 card reader Read 19MB/s Write 19MB/s
New USB-c card reader Read 91M/s Write 49MB/s

The results speak for themselves.

In some ways it is good to know that your results for USB2 replicate mine.

And I have to admit that plugging a cardreader into a direct interface with the motherboard rather than the front card reader panel would not have occurred to me as a potential benefit. Thank you for the tip.

Perhaps I should I shall put an external card reader on my wishlist for my birthday.

[Manfred M]

The other advantage you will find with an external card reader, especially a higher quality one is that the ones built into the computer seem to be designed for very limited use and are somewhat fragile.

Twice during courses I have taken I've been in the classroom when someone's internal reader decided to break and not release the SD card. In both cases the card could be eventually be removed, but it was damaged and the internal reader was destroyed. The instructor teaching the course told the class that in his experience this was quite typical and he sees one incident of this happening pretty well on every course he teaches, so he highly recommends a high quality external reader.

[Manfred M]

In general an usb3 is partly blue inside.

The cables are definitely different so that is the easy part. Unfortunately computer manufacturers don't necessarily do this when building the machines. On both my computers (desktop and laptop) the USB ports on the machines themselves are not identified in any way and the part that is blue on the USB cable, the corresponding part on the computer itself is black. One of them has a tiny USB 3.1 marking near the port (around the back of the machine) the other has no markings whatsoever.