Late last year we bought on of the new Transcend 790 series USB sticks, 128 GB for general removable storage use. The 790 series have a 5 year warranty.
Transcend said the part number is TS128GJF790K.
We notice the performance was quite inconsistent which suggested that the USB stick was not exactly a high-end unit. While no errors were every presented, occasional when copying a large number of files it would passe for a moment. This could be due to the controller mapping defects while writing or it could be doing a TRIM operation.
The USB stick failed recently and we contacted Transcend via Twitter.
Eventually they got back to us with a tool to check the firmware. Unfortunately the stick does not get recognized and throws device exceptions. So the Transcend diagnostic is not helpful in our situation.
We tried the stick on several machines and the fault was present on all machines.
Transcend Information , Inc
1645 N BRIAN ST
ORANGE CA 92867-3423