What computer specs Frank?
Mac? PC?
What mainboard, what memory .. etc.
USB3 is now slow, and 120Mb/s is top whack for USB3.
USB3.1 allows a usable speed upgrade over USB3.
If you look into USB3.1, a few things to be mindful of:
1/. ASM chipset only!! that is, AMS1142 is the normal Asmedia chipset used by most PCI-E to USB3.1 devices, but if you happen to locate any using the ASM2142 or ASM3142 chipsets even better.
Note on the topic of PCI-E to USB devices .. just because its says PCI-E to USB, doesn't make them all the same. The adapting chipset used is absolutely critical in terms of speed.
If you're not sure of the chipset used, and the adapter card maker doesn't specify then avoid. Chipsets brands I now avoid like a plauge/virus/demonic annoyance!! .. are VIA and JMicron
2/. If you plan to keep PC into the future, then having a USB type C connector can be handy.
SO!! if you want a bit more USB speed, look for USB3.1 devices, avoid non Asmedia chipsets(Intel are also good, but you won't find any on peripheral cards).
There is a brand of peripheral card I'm looking into ATM called Speed Dragon(google that name and browse their site).
The problem is, I can't find any retailers selling their products, and I think the reason is that Speed Dragon are wholesale manufacturers that may only make generic parts where other brands place their name on the product.
For USB3(and 3.1 too) check for updated drivers for your chipset(s).
My mainboard has both USB3 and 3.1 onboard.
USB3.1 is Asmedia chipset. USB3 is Via chipset. I don't have any adapter cards(but IU've been looking into them)
I have a Volans USB3.1 docking station(for HDDs) on the USB3.1 port(USBtype C connector).
I also have multiple USB3 devices, one of which is a USB3 HDD enclosure.
Both HDDs are WD blacks .. quite fast for mechanical drives.
I've done Crystal Diskmark testing. They can do approx 140-150MB/s write speeds, just a touch more read speeds.
On the VIA chipset USB3 line, both those drives struggle to do over 60-70MB/s for more than a quick burst, sustained they can only really achieve 50-ish MB/s
On the Asmedia chipset USB3.1, they easily do 125-140MB/s transfers(depending on file types).
Prior to fully setting up my PC, I quickly tested one of my SSD drives. I have two. 1 M.2 Samsung 950 and one Kingston SATA.
I plugged the Kingston into the USB3.1 docking station just to see, and it easily sustained 400+ MB/s doing a proper file transfer. files were two large 1+ Gb movie files just for testing.
Crystal Diskmark gave it a 480MB/s rating on that USB3.1 line!
Note tho that it's not all roses, and again it all comes down to chipsets and devices used.
Some devices seem to be optimised for different chipsets or something.
I have a USB3 Lexar CF card reader.
I plug it into various ports for testing, but generally keep it in the USB3 port because:
I have one Lexar CF card for the D800E, 800x speed rating. In the USB3.1 port, it never reads over 100MB/s, writes at about 60-70MB/s
I have one Patriot CF card that only works in the D300(ie. this card won't work in the D800E) Lexar card works in the D300 too tho.
On the USB3 Lexar card reader: Lexar card writes at 50MB/s max. never seen more than this no matter what files I transfer to it.
Patriot card writes at 60-70MB/s depending on files used for transfer.
Because of that, there is no point trying the USB3 Lexar reader on the USB3.1 line .. no speed advantage in doing so, so the USB3.1 line (for now) is reserved for the USB3.1 docking station.