Driver over run stack-based buffer error with Zotac GeForce GT 620

I have an ASUS p5gdc-v Mobo(old i know but its what im working with as of now). I recently bought a Zotac GeForce GT 620 graphics card and after installing the hardware i changed the GPU Priority to anything but internal GPU and i always get the blue screen error until i change the vga priority back to internal. I dont think its a virus and everything i have read up on says that my Mobo has PCI Express x16 1.1 and thats what the card is "compatible" with. i was wondering what i can do to finally fix this and use my 2gb video card?