USB Flash Drive Performance

I have 3 Usb 2.0 drives. A 16GB Kingston, 8GB PNY and a 4GB PNY. When I copy a 1GB file I the Kingston runs at 10 MB/s for the first 30% of the file then drops off to 5 MB/s. The 8GB PNY has consistent 10 MB/s transfer speed. The 4GB runs at 5 MB/s.
All 3 run at ~25 MB/s when copying back to computer.

If flash just stores on memory internally, then why the speed difference?

Thought it might be USB protocol overhead but copying back to computer they run about the same.

oneextraid said:

If flash just stores on memory internally, then why the speed difference?

Apparently, higher-binned flash memory chips and/or better memory controllers increase transfer speeds........

Different drives use different chips and different controllers for those chips. Not all flash drives are created the same. You also didn't mention how the drives are formatted, which could potentially affect performance as well.

As for the speeds copying back to your computer, that is probably governed more by the USB ports. Most likely, those flash drives all have higher read speeds than your USB ports support, so they all top out at the same speed. Typically, in any kind of flash memory, read speeds are higher than write speeds.

The 16GB and 8GB are NTFS. The 4GB is FAT32. I would agree that higher capacity drives would/should be faster except for the 16GB Kingston. It slows to 5MB write speed after about 100MB of transfer. Like it has cache.

Thanks for the responses. Guess it is like race cars. All are fast, some are faster.