The maximum flow rate depends primarily on the motherboard (including chipset) and the connected device.
On my old PC into Core2Quad Q9550, chipset E43 / ICH10 I maxes out at 170MB / s write and 150Mb / s read with a Samsung SSD 840evo mounted in a housing Inateck FE2006.
In USB 2.0, the same device is respectively 37 and 32Mb / s.
It is best to use a PCI Express x4 or x16 PCI Express with revision 2 or 3 (see the motherboard manual)
The PCI Express x1 ports are generally standard revision 1 and brident flow.
Satisfied with this product and usually this Inateck brand I recommend.
