I had my old Radeon x850 XT working fine in Win7 x64 (installed using the "Disable Driver Signature Enforcement" advanced boot option), but when I upgraded to Win8 x64, the driver stopped working, and trying hte same method I used in Win7 didn't work. After getting a "Not compatible with Windows 8" response from AMD support, I did some digging and was able to get it working.At a high level, the problem is simply that the "10-2_legacy_vista32-64_wdm" is not digitally signed, and Windows 8 absolutely will not install 64-bit kernal drivers unless the are signed. ATI/AMD *should* sign the driver, since it only takes a few minutes and would cost them nothing. As they haven't done that, *you* can sign the driver yourself. It's a bit involved, but if you're willing to do some homework you can make this work.The simplified overview is that you use the inf2cat.exe tool from the (free) Windows Driver Kit on the *.inf file too produce a valid *.cat file. Then you use signtool.exe from the (free) Windows SDK to digitally sign the *.cat file. Since you (most likely) do not have access to a valid Software Publisher Certificate to use for signing, you have to use a self-signed test certificate, and then put your computer into test mode to use it. None of these actions would be necessary if ATI/AMD signed the driver themselves. Google these tools and you will find plenty of information. I was not at all sure I could do this when I started, but in fact, after learning what you need to know, it's not that bad.My Radeon x850 XT is now running at 1920x1080 in Win8 x64 retail. It can be done.

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This stuff should be easier...

It is, it's called using WDDM 1.2 capable cards (HD 5000 series and above) when you're spending over $100 on an "update" to Windows 8

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Crosshair IV Formula, Phenom II x4 965 w/ Corsair H60, 8 GiB OCZ Platinum DDR3 1600, XFX HD 7970 Ghz, 512GB Vertex 4, 256GB Vector, 240GB Agility 3, Creative X-Fi Titanium w/ Creative Gigaworks S750, SeaSonic X750, HP ZR2440w, Win 7 Ultimate x64