If you did a fresh install of Windows 7, make sure you install Windows 7 SP1.
A lot of Windows 7 drivers were not included in the original release.
http://windows.microsoft.com/installwindows7sp1
The manufacturer does not list a specific driver for this card( although it does list it as being Windows 7 compatable) so likely you will find it by updating Windows 7.
http://www.siig.com/hi-speed-usb-5-port-pci.html
×