SONNET PCIe USB CARD NOT WORKING IN MAC PRO EARLY 2009

Hello

i'm running a MacPro Early 2009 on Mavericks and i'm trying to get a Sonnet PCIe USB 2.0 card installed.

the card appears in the system information when I install it but any device I plug on it is not recognized, as if it lacked power.

tried reseting PRAM, changing slots, emptying caches, anything I found on the web...nothing worked

so what could cause a power shortage to the card ? any way to check if the system monitor if power actually reches the card ?

i've bought the card a while ago, before mavericks, problem was the same with previous OS X versions

thanks for your help