1) Download the newest version of Display Driver Uninstaller (DDU) and extract it to your location of choice (I just extract it in a folder on my desktop). DDU seems to get updated often, sometimes even multiple times per week, so always check for the newest version
NOTE: If you don't use any additional GPU software (EVGA Precision, MSI Afterburner, Radeon Pro, etc.), more than one monitor, SLI/Crossfire, or 3D (particularly Nvidia 3D Vision) then skip to step 7.
2) If using multiple screens (independent, "eyefinity"/"surround", etc.), go back to single screen mode with the outer/remaining monitors disabled (done in NVidia Control Panel/AMD Catalyst Control Centre [CCC])
3) If using 3D, disable it (uncheck "enable stereoscopic 3D" in the Nvidia control panel, I'm not sure about other companies' 3D, I use Nvidia 3D Vision 2

)
4) If using SLI/Crossfire, disable it in the GPU control panel (NVidia Control Panel/AMD Catalyst Control Centre [CCC])
5) Set all overclocks, and such, in any additional GPU software installed (EVGA Precision, MSI Afterburner, Radeon Pro, etc.), back to default (should be a "default" button)
6) Use the free program Revo Uninstaller in it's most thorough/advanced mode to fully uninstall any additional GPU software (EVGA Precision, MSI Afterburner, Radeon Pro, etc.). Just the 3rd party stuff though; Original AMD/Nvidia drivers and control panels will removed in the next few steps below
7) Restart in safe mode
8 ) Use display driver uninstaller (DDU) in safe mode to uninstall your drivers. Always make sure you select to uninstall/clean everything you can from the brand you choose (eg. for Nvidia - PhysX, 3D, any audio stuff, everything), even if you think or know it wasn't installed. Also, always make sure to select the "Remove C:\AMD and or C:\NVIDIA folders" option. When you proceed with the driver cleaning, choose the option that DOES NOT restart/shut down the PC. Then click o.k./exit/close when it's done cleaning, DDU will close, open it back up, make sure everything is selected again, and this time make sure you choose the option that DOES restart the PC (or the option that fully shuts down the PC if you are going to physically be changing your GPU).
9) After restart, use the free program CCleaner's registry cleaner and delete/clean any AMD, NVidia or additional GPU software (EVGA Precision, MSI Afterburner, Radeon Pro, etc.) files it may find
10) Restart PC
11) Install AMD/NVidia drivers and always choose "custom" install and just install the minimum of what you need. The following is what I usually install/don't install:
A) For NVidia, I checkmark the following:
- Graphics Driver
- 3D Vision Controller Driver (for 3D, and possibly needed in order to use the amazing 2D Lightboost/strobing hack)
- 3D Vision Driver (for 3D, and possibly needed in order to use the amazing 2D Lightboost/strobing hack)
- PhysX System Software
- Also, make sure to checkmark "Perform a clean installation" below
B ) For NVidia, I make sure the following are NOT checkmarked:
- HD Audio Driver (or generally anything related to audio)
- Miracast Virtual Audio (Allows rendering or streaming of graphics, video, and audio over WiFi to Miracast displays. Windows 8.1 and later) - no thanks
- NVIDIA GeForce Experience (unfortunately you need to install this entire piece of bloatware if you want to use Shadow Play)
12) If you aren't prompted to restart at the end of installation, then restart anyways
NOTE: If you don't use any additional GPU software (EVGA Precision, MSI Afterburner, Radeon Pro, etc.), more than one monitor, SLI/Crossfire, or 3D, then skip to step 17.
13) Upon restart, install any other GPU software you wish (EVGA Precision, MSI Afterburner, Radeon Pro, etc.)
14) Restart
15) Setup SLI/Crossfire, and/or triple screens, and/or 3D (3D last)
16) Restart
17) Open up Windows Command Prompt with admin rights. It's called "Command Prompt (Admin)" - make sure your PC is in your gaming mode (any overclocks you use for gaming like CPU, GPU, etc.) - type "winsat formal -restart clean" (without the quotes) and press enter on your keyboard. Give it a few minutes to do it's thing. Once done, close the windows by typing "exit" (without the quotes).
18 ) Restart PC and PLAY!
NOTE: You probably don't need to do steps 2, 3, 4, 5, 14, and 16, it's probably OCD on my part, lol, but I do things as thoroughly and one-step at a time when it comes to this sort of stuff (drivers etc.).
NOTE: For ISI engine based game users (rFactor 2, Game Stock Car, rFactor, Formula Truck, GT Legends, GTR 2, Race 07, Raceroom Racing Experience, ARCA SimRacing, etc.) click "configure sim", or the configure program for the specific game, set all your settings, click OK. If my previous settings are still there then I choose a wrong resolution, press OK (window should close) then I open it again and set my desired settings. I do this so that the game sort of re-grabs my PC info.
Now go race!
P.S. I have never had an issue with a GPU driver installation/un-installation in my life. Not a single one going back 15 or so years with all sorts of hardware/software (AMD/Nvidia GPU, AMD/Intel CPU, Win XP/7/8.1, 1x/3x monitor, 1x/2x/3x GPU, 2D/3D).