Viper II / Savage 2000

I have a Diamond Viper II video card and I can’t play NFS5 - Porsche Unleashed and Baldur’s Gate II - Shadows Of Amn (with 3D acceleration enabled). The screen keeps blinking and flashing so I can’t play. If someone knows how to fix it please email me ( cause I’m going crazy with this card. I have a Athlon 750, Asus A7PRO, 128M RAM.