Sounds like it's not your RAM. Well... like I said, you're just going to have to do some trial and error to try and find the problem.
I did stumble across this thread at Microsoft's website. It looks like there are a lot of people suffering from the same problem that you are. Lots of different fixes have been suggested, so you should give them a try.
One thing you should try is uninstalling your graphics driver and installing the latest graphics driver from nVidia's website. Use the driver removal tool below to make sure that you completely remove the old driver before you try installing a new one. And make sure that you restart the computer between uninstalling the old driver and installing the new driver. If you don't completely removing the old driver then you could have a driver conflict like you're having now.
Guru3D driver sweeper
I did stumble across this thread at Microsoft's website. It looks like there are a lot of people suffering from the same problem that you are. Lots of different fixes have been suggested, so you should give them a try.
One thing you should try is uninstalling your graphics driver and installing the latest graphics driver from nVidia's website. Use the driver removal tool below to make sure that you completely remove the old driver before you try installing a new one. And make sure that you restart the computer between uninstalling the old driver and installing the new driver. If you don't completely removing the old driver then you could have a driver conflict like you're having now.
Guru3D driver sweeper