Have you tried the Helproom with your problem? You get almost instant support from any one of thousands of knowledgeable folk!
Normally to find a fault, a company would do a 'soak test', putting the card into a PC and running a game, benchmark, movie, or diagnostic test such as DirectXDiag - whichever suits the problem.
Not many boards out there support DX9, as it now includes certain advanced rendering features that require the card to do. But there is no problem if you have upgraded to DX9 - it will cause no known issues.
I would think that the issue you have would be related to your PC's configuration, but that could be found out through the Helproom. Just post in there with your OS, brand and specification of PC and a description of the problem.