You need to install the Windows 7 64-bit graphics driver for your PC, laptop or motherboard model as appropriate:
a) If it's a factory built PC, download driver from the PC manufacturer's website.
b) if it's a laptop, download it from the laptop manufacturer's website.
c) If it's a custom-built rig, download from the motherboard manufacturer's website.
If none of the above have Windows 7 drivers for your model, you cannot run Windows 7 on it.