[SOLVED] Irregular USB3 Speed - Either 40mb/s or 100+mb/s. All USB3 ports

[fredfinks]

Win10
z370 mobo
USB3 ports - Front and back. Intel chipset (non 3rd party controller)
USB3 drives - Sandisk extreme, Startech USB3 dock, etc. (all capable of well over 40mb/s)

Regardless of what fast USB drive i have in, my USB 3 speed either gets its correct speed or is limited to 40mb/s. Sometimes i copy at 40mb/s, eject, reinsert and the speed goes to what it should be - or vice versa. Its hit or miss, regardless of contents of drive (most of time drives are empty or nearly empty) or chosen port. Unfortunately, lately, its mostly the 40mb/s cap

In device manager i have 4 USB controllers listed:

Generic USB hub
Intel(r) USB 3.0 eXtensible host controller - 1.0 (microsoft)
USB composite device
USB Root Hub (USB 3.0)

Not sure which one is used when i connect. They are all updated (or at least win10 thinks so)


Any ideas? Appreciate any help!

 

[LinuxDevice]

Not really an answer, but many drives have cache. The cache operations are always much faster for short bursts, but eventually you get to the point where the drive itself will be the speed limit. In cases where some part of the drive is read multiple times, or when a write is immediate read, you will use cache or buffer and performance will go up dramatically for a short time. You can't judge what sustained performance should be based only on the link speed (in this case USB3). Link speed is only a cap.

Add to this that when you write somewhere, you must read from somewhere else to get what you write. Source and destination limitations and interactions can complicate performance.

I know nothing about the particular memory you are using, but you'd need to consider any ratings for "sustained" reads/writes of both the source and destination.