USB 3 transfer speed falling after 10 seconds?

So I've had a lot of trouble with USB3 - I've never really had the consistent transfer speed it's supposed to provide.

I know that initially the RAM caches the transfer which is why it starts very high, then falls, but mine is falling to sub-20MBs.

As in, copying TO the flash drive - I never get the 70MB+ speeds USB3 is supposed to be capable of. Sometimes starts there but quickly drops. And yes, my flash drive is plugged into USB3 slots.

This is the case with both flash drives I've tested on this system - and yes, my drivers are USB3 too. And it happens whatever the size of the file.

What can cause a drastic drop in transfer speed?

EDIT: just to point out copying from the drive to the PC is perfect - 130MB+. It's copying TO the drive, that's the problem. Cheers.

DannyG13 said:

I know that initially the RAM caches the transfer which is why it starts very high, then falls, but mine is falling to sub-20MBs.

That's about right. Most USB flash drives are limited by the speed of the flash memory in them, and most of them cannot write as fast as the interface will allow. Can you give the brand and model numbers of the drives?

On many drives the Read and Write Speeds are not the same , read can be quite high but write is usually another story especially with cheaper drives.

Mystere said:

That's about right. Most USB flash drives are limited by the speed of the flash memory in them, and most of them cannot write as fast as the interface will allow. Can you give the brand and model numbers of the drives?

I believe the fact my drives are extremely inexpensive has contributed to this. Read speed is cheap, write on the other hand is not. The best one I have is a 64GB Sandisk SDCZ43-064G-G46 - literally about £10. Honestly thought I'd get high write speeds but evidently not! The benchmarks I've seen online suggest this type of flash drive writes around 15-30MB or so.

Kbird said:

On many drives the Read and Write Speeds are not the same , read can be quite high but write is usually another story especially with cheaper drives.

Yeah, 'cheaper' was my downfall here I think!

I recently bought this drive:

https://www.pny.com/turbo-3-0-usb-fl...P-FD64GTBOP-GE

Except I bought the 256GB version, and have been quite surprised by both the read and write speed. 300+MB/s. Quite good for such a cheap drive.

Mystere said:

I recently bought this drive:

https://www.pny.com/turbo-3-0-usb-fl...P-FD64GTBOP-GE

Except I bought the 256GB version, and have been quite surprised by both the read and write speed. 300+MB/s. Quite good for such a cheap drive.

That's impressive. 300MB write speed?!

DannyG13 said:

That's impressive. 300MB write speed?!

Actually it was more in the upper 200's, but still yeah, it was quite surprising.