Question USB3 Data transfer throttling to 40mbps?!

[jacobgibbins]

Hey everyone,

Please help! This issue only seems to affect USBA-C cables. Its the change from A-C or C-A which is the issue.

• So this is on multiple windows 10 machines (a desktop and laptop), same issue.
• I have tried transferring from/to SSD drives, CFExpress cards, internal Nvme drives which work 100% fine with speeds of 300mbps+ if I use A-A or C-C cables. So the media at either end of this process is zero issue.

I cant seem to get data transfer speeds over 40mbps (USB2 threshold) when ever I use a cable that goes from USBA - USBC. Either with a cable made with those connections from factory, or with USB3 rated adapters.

All ports, front, back, with hubs (plugged into 10gbps ports), on both machines work 100% fine with transfer speeds of 300mbps+ if I use a cable which is the same both ends. A-A or C-C is fine.

BUT! If I try the same drives, and ports which work 100% fine with a cable the same at each end, with a cable that has A one end and C the other end, BOOM ... 40mbps max data rate.

HELP! WHY!?

Thanks, Jacob

 

[rgd1101]

where did you get this usb a to usb c cable?

 

[jacobgibbins]

I have tried multiple ones.

• The fast charge USB3 cable that came with my Oneplus 6pro phone
• This one from amazon yesterday: https://smile.amazon.co.uk/gp/product/B07PQXTH41/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
• Cable and C to A adapter that came with the angelbird CF card reader.

All the same issue.

 

[jacobgibbins]

Even more info... I have downloaded FastCopy software...

Which if I transfer from a CF Express card ( Rated to 1500mbps) to my Internal Nvme drive ( similarly fast rated) it is showing the read and write speed to be 900MBPS, but the transfer rate is still only 40mbps... so the port, cable, drives are fine, but for some reason the data transfer is being throttled... why!?