Erratic data transfer rates to usb memory stick

[millview53]

Hi all,

I am trying to copy large files from a hdd to a SDHC memory card via a sandisk card reader and am getting really erratic data transfer rates (see image, one hdd is constant and the top one is very erratic) is the hard drive close to failing? I assume so but just wondered if anyone had a different theory......
Using win 8 by the way if that makes any difference....

 

[rpstewart]

2 different source disks? Was the copy running to the SD card from both at the same time?

Is the top one the system disk? What else was accessing it at the time?

 

[millview53]

both are storage drives. I wasn't running them both at the same time just using the graph to illustrate the difference in transfer rates. the bottom drive transferred to the card at a constant rate whereas the top one would go for a while then the transfer rate would drop to 0 and after a while start up again, then stop etc...etc...