AMD did not release Win 8.1 driver for A960D+'s HD 3000 on-board VGA.
However, you can use HD 3000 Win 7 driver manually install to support it.
Here is the driver download page.
http://support.amd.com/en-us/download/desktop/legacy?product=legacy2&os=Windows+7+-+64
For installation process, please refer pictures here.