Tutorial: How to spot a fake memory card

Slow memory card? Buffer overruns? Data corruption? Maybe you are dealing with a counterfeit memory card!

In a previous popular article on my blog I covered the required minimum speed of memory cards for my Canon DSLR. Looking at some of the feedback I got on the article at the time, it appeared that some people were experiencing speed issues even though they owned high performing cards. These cards should have performed better than the ones I was using and much better than what Canon recommended in their user manual. Among the issues people experienced were most notably buffer overruns, unstable performance, slower transfer speeds and corrupted data.  Buffer overruns typically occur when the camera cannot write fast enough to the card and hence starts losing some of its data. And corrupted data… well you have certainly come across that in your computing life at least once!

The feedback I got from some people really surprised me because, I had never used any high-end card, yet I never experienced a single issue - neither when filming in high-def nor when taking burst shots. So I started researching the topic a bit and found out that the issue at hand is much larger than what I initially expected.  As it turns out, the world is plagued by an abundance of fake memory cards, advertising higher capacities than they can deliver! Of course we all know that there a fakes and imitations out there, but one tends to imagine they are limited to shady vendors or certain regions of the world. Yet you couldn’t be further from the truth! Yes China is a major player in counterfeit memory cards but considering the prevalence of memory cards in digital devices today, the physical size of the product and its market value, it is easy to understand why these products attract counterfeiters of all sorts.

So, to understand how that possibly affects your memory card and therefore your digital cameras, devices, phones, etc it is useful to understand how real cards are manufactured in the first place.


Where are fake memory cards coming from?

When a manufacturer produces memory cards, these are of course being quality tested at the end of the production process. Depending on the outcome of the testing, each card is essentially validated for a certain capacity. So a card could be tested against a 64GB test and fail it, but succeed in the subsequent 32GB test. The manufacturer then labels and sells the card with a 32GB capacity even though the card is inherently not different from a 64GB one.

Now this is where shady resellers step in. They buy or source low cost memory cards with little memory, e.g. a load of 4GB cards, and reprogram the card controllers to a higher capacity, e.g. 32GB so that when you insert the card into your device it actually appears as a 32GB card. An unsuspecting buyer inserts the card into his camera or computer, and the system acknowledges the 32GB card because of the reprogrammed controller. You don’t suspect a thing because your camera hasn’t yet tried to write to each and every sector of the card. Like most people, you probably don’t take 800 pictures in a row without transferring the pictures back to your computer and erasing the card to make room for your next shots. So, like the average user, you will probably not run into problems during the your first uses of the card. But then, one day you leave for a photo shoot or on vacation and all of a sudden you cross the threshold of 4GB on your counterfeit 32GB card and here the problems start. You start getting read/write errors and data corruption kicks in… and your shots are toast! For people involved in hi-def shooting, where the files are significantly bigger and the read-write performance is essential, this issues will appear much sooner.

By now you probably think “hey I bought my card from a reputable seller online, this doesn’t concern me.” Well unfortunately you are still quite at risk. As you know, the price difference between a 4GB and a 64GB (or higher) card are quite significant. There is a lot of money at stake and counterfeits are difficult to spot. So the market is inundated with fake cards people, and even resellers, believe to be genuine. Many resellers buy their stock from third parties and can’t tell the difference… which means that the cheap electronics store around the corner that manages to sell memory cards at that really great price… could be selling fake cards… without even knowing it!

It is a massive industry and there is plenty of money at stake, so if you experience any problems with your card, you should check it out or return it to the seller.


How to identify a fake memory card?

While there are no guaranteed rules about identifying a counterfeit card, there are sometimes a few give-aways that should make you more cautious:

1. Check the manufacturer's website

A good starting point should be to go the manufacturers website and see what tools they make available to validate their own brand. Most manufacturers these days offer some quick verification tools that will give you an answer within the minute. While not practical before the purchase simply because you do not have the card and packaging in your hands yet, it is still recommended to perform the test as soon as you can. Manufacturers will ask you to input a serial number, the bar code from the packaging and a few other details and tell you if the card is genuine. If you buy in a retail shop and have access to the internet on your mobile phone, perform the test while in the shop, even when shopping at more established retailers.

As an example, have a look at Kingston's verification page: Official Kingston Product Verification Page

See this sample from a Kingston memory card packaging:


2. Have a look at the packaging

Most established manufacturers plastic wrap their cards with heavy and solid plastic, include warranty cards, usage instructions and display a hologram on the packaging. While everything can be counterfeit (and is), even the hologram, it takes more effort to duplicate all this packaging, which rules out part of the cheaper knock-offs out there. Never buy a card that is not sealed in the original manufacturer box!

3. Examine the memory card itself

Does it have a serial number? Again, not a guarantee for being the real thing, but it’s another step the bad guys skip from time to time.


4. Test the card… the closest you can get to a real answer

This one is both the easiest and most difficult method. Easiest, because testing the card will give you the most accurate out of all the points above, but the most difficult because it happens AFTER the purchase process… when it might be already too late.


How to test your memory card for genuineness?

As per my explanation above, just taking a few shots is not enough because the first GB of the card are probably in good working order. So to establish whether you card is good or not you need to perform some additional tests

1. Format the card

Do a FULL format… do not use the 'Quick format' option your operating system might offer you by default. A full format does more writing to the card than a quick format. If the format fails, if you get errors, you are likely to either have a genuine but defective card or a fake one.

2. Write/Read test the card

In Windows with H2testw 1.4

Download H2testw 1.4

Download H2testw, connect a card reader to your computer and insert your memory card. Follow the instructions provided with the software. The software will write dummy data to the entire card and read it back. It will then compare the written and read data to ensure the card works well. If you get errors like in the example below, you have a fake card.

Here is a sample output for a fake 64 GB card (a 4GB card sold as 64GB):

The media is likely to be defective. 
3.8 GByte OK (8084847 sectors) 
58.6 GByte DATA LOST (122921617 sectors) 
710.5 KByte overwritten (1421 sectors) 
7.6 MByte slightly changed (8 bit/sector, 15630 sectors) 
58.6 byte corrupted (122904566 sectors) 
710.5 KByte aliased memory (1421 sectors) 
First error at offset: 0x000000003cef8470 
Expected: 0xeb7ac43a237c5170 
Found: 0xeb7a843a237c5170 
H2testw version 1.3 
Writing speed: 9.24 MByte/s 
Reading speed: 10.8 MByte/s
This is 4GB USB flash drive not a 64GB USB flash drive. It is of poor quality. A 4GB drive it should be about 3.81 GB formatted (which it is here) but this drive also has 58.6GB lost. This indicates in low level formatting a lot of bad sectors had to be locked out. Usually flash chips like these are rejected for major brands and should be destroyed. Unfortunately instead of the furnace flames these chips are leaving the back door of factories to be resold.


In Mac OS X with F3

For Mac users, use the OS X port of H2testw by following the link below:

Download F3


Final Words

My recommendation would be to only buy from established vendors, whether online or retail, to whom you can return the card if there is any problem. Be wary of too attractive prices and non-specialized sellers. Not all are fraudsters, but many buy their own stock from what they think are reputable third parties to resell them to you. Unknowingly they resell fake memory cards, thinking they are making a good mark up. And if your card indeed is a fake one, your path to a refund my be more difficult.

If you already have a bunch of cards and never encountered an issue, that is great! Hopefully you are in possession of genuine cards. It doesn't hurt to perform the Write/Read tests as per above to make sure you have the real deal… because if you don’t, you are likely to only find out the day you are on holidays or on a photo shoot… and then it might be too late, you might have lost a few precious hours or memories.