Windows 8 Transfer speed drop USB 3

Hi everyone, first post to this forum -

I am curious about windows 8 transfer speeds. I'm currently running a Dell XPS 1647 (mid 2010 model) with a USB 3 card from Startech installed in the expressport. It works great, but windows pretty consistently does this thing where if I'm transferring files, it will start fast and then slow down by at least 50%. I have attached a photo of this situation. In this case, I was transferring roughly 500gb of files from a LaCie drive (7200RPM) using eSata to a Western Digital drive 2.5in external drive using USB3. to about 70% of the transfer I was getting 80mb/s transfer speeds, then it drops to roughly 26mb/s for the remainder. This hasn't just happened on my laptop, on my new desktop running W8 Pro, the same thing can occur.

Is there a reason for this? Is it a windows thing, or a hardware thing? I find it does it on USB keys as well - starts quick, then quickly drops to about 20% of the speed.

Any help in figuring out what causes this would be great! thanks!

James

The more data you transfer the more it becomes fragmented and trying to figure where to put it on the source drive, especially when it starts to get full.

Hi, I am having the same issue
here I'm copying from my 128Gb SSD to my 1Tb hard drive which is almost empty, so there shouldn't be any problem with that. Also I noticed that it's not much the amount of data I copy which determinates the moment it drops, but just the percentage accomplished and remaining, always around the same moment whatever the file's size is.
The transfer began at 700Mb/s and droped to 100Mb/s