In all respects, this card works very well (write speeds regularly exceeding 70MB / s to a Seagate Expansion USB 3.0) ... once the correct driver installed in Windows 7.
In this regard, thank you to Jean-Luc and the rest in return for that. In the absence of instructions, it would have been a little "galley" otherwise.
Note that the driver in question is a micro-program "Renesas Electronics USB 3.0 Host Controller Driver" in which the process (rusb3mon.exe) must remain permanently active, particularly if the internal 19-pin port is used. Beware of automatic genre optimization programs TuneUp Utilities!
For those who find it difficult to find the "good" driver for their config Win 7 x64, I suggest they take a look here: "3w" .usb3-drivers.com / download-Renesas-usb3-driver-for-Windows7 -64bit
Another small note: to connect or disconnect the power supply or the USB 19-pin, well maintained between 2 fingers the catch of the card before plugger cables. More preferably, spray a small amount of silicone on the outside of side plastic cable crimping.
Indeed, welds seemed to me a tad "light" on the first try.