I recently bought a Nanoflash with one Sandisk Extreme 32G card
Everything works fine up to 280 Mb/sec
Sandisk Extreme ser.nr. in small lettering on the side: BM100812993B
FiFo indicator stays at 0% so that is OK
Sandisk Extreme 8G is working fine as well.

Bought 4 new Sandisk Extreme 32G cards, from a different vendor,
packaging and card look identical to the first one.
They have a different ser. nr. on the side: BM100913934B
They are slower and can not sustain 280 Mb/sec.
FiFo is continously creeping up to 100% and Nano switches back to 220 Mb/sec on one card even to 140 Mb/sec.
I ordered 4 of the same cards from again a different vendor, the ser.nr. is again BM100913934B
These cards were also slower, could only sustain 220 Mb/sec.

So 8 cards are slow, they all have the same ser.nr. (or is this a batch nr.)

Anyone encountered something similar ?

I bought some supposedly class 6 Sandisk 32GB cards on ebay. They didn't work at higher data rates and when I checked the card info, they came back as class 2. The seller admitted he got them from China and refunded me in full. He even added a bit for my trouble.

I think I got away lightly and buy from reputable stores now.

They were not especially very cheap and came from well known vendors.

If the numbers on each of the 8 cards are the same I supposed they are batchnumbers.
So it might be a faulty batch or they are fakes.

Are the numbers on cards serialnumbers and therefore unique numbers?

Dear Peter,

SanDisk is a well-known brand.

Counterfeit SanDisk cards are on the market.

We always recommended purchasing CompactFlash cards from a reputable vendor.

Sometimes, but not all, one can detect counterfeit cards by the attractive, lower than normal price.

Do the cards appear identical in every way to your original card, except for maybe the serial number?

You have certainly used the tools that we provide to check the performance of your cards, and that is great!

If you have genuine SanDisk cards, I would ask to have them replaced.

If you have counterfeit cards, contact your dealer, or if you purchased them from an auction site, take appropriate actions.

You may also be able to get help from your credit card company, if you used a credit card. The same may apply to PayPal.

Yes they are identical in every way to the one Sandisk 32G CF card that is functioning normal.

However they all have identical numbers, a different number than the 'good' one.

Are cards with identical numbers a common thing ?

BTW, I will send them back to the supplier, they are reputable companies so no problem.

Dear Peter,

I do not know if that number is a Serial Number or Part Number.

Just to let you know that these cards were indeed faulty allthough they seemed to be original Sandisk.
I received new Sandisk Extreme 32G cards, everything is fine now.
FiFo stays at 0%, so these cards do handle 280Mb/s OK.
I'm happy.