Hi axelay, welcome to SAF
As a first thought, you may carefully browse your BIOS settings to see if all video/graphic properties are correctly set to your new videocard (disable onboard video if it's any). Also, take a look at the troubleshooting guide shipped with the card.
It happens sometimes that a brand new card does not work and must be returned to the vendor. If you have another computer around, you can try to install it there, to see if the card works on it...
ATI website has also some interesting features, including auto-detect some products. It may not hurt to browse/ask ATI support on this issue.
https://support.ati.com/ics/support/default....asp?deptID=894Chris