You need your chipset drivers proxie. It is important to have them. Windows apparently "provides" them for you sometimes...but it is always best to go to the manufacturers website and get them off there as they are usually more up to date and more complete. They give you up to date drivers for your pci express port, processor, hard drive, blah blah blah.
If yours is an asus macc...you should have too many problems finding it on their website in support. I will look tomorrow if you can't find it, but it should be self explanatory. Then I would proceed by going back to Nvidia and finding your graphics, updating your sound driver (if possible), and making sure nothing else is found to be update-able in windows updates as it sometimes finds drivers that are more difficult to find online.