OK. When you say you don't see it in device manager, I take it you're seeing a "Microsoft Basic display adapter," and when you try to install the proper AMD driver there is a serious error of some sort. I also take it when the PC recovers the driver is reverted back to Microsoft's generic driver.
Just to make sure, are you certain you are running the correct installer for the driver?
Unfortunately any benchmarking tool or utility we might use to try to determine the health of the card won't run without a proper driver. Also I can think of few ways to troubleshoot the possibility of an error in Windows without a reinstall, whether by using the Reset function in Settings or using the install disk again.