You should be extremely cautious about upgrading to the Windows 8.1 Release Preview. Each of your apps, and all of your desktop software, must be reinstalled when the final code is released later this year; it is a detour to a dead end.
If curiosity overwhelms reason, and your graphics card was made by AMD withing the last few years, you will at least have a driver available.
It would be a good idea to refer to the AMD article to ensure that your specific model is supported. The driver covers many graphics cards from the Radeon, APU, and FirePro product categories. Many models are certified against Windows Display Driver Model version 1.3 (WDDM 1.3) although some, pre-Graphics Core Next architecture (as far as I can tell), are left behind with WDDM 1.2 introduced with Windows 8.
WDDM 1.3, new to Windows 8.1, allows for a few new developer features:
Enumerating GPU engine capabilities
- A DirectX interface to query card capabilities
- Helps schedule work, especially in "Linked Display Adapter" (LDA, think Crossfire) configurations.
Using cross-adapter resources in a hybrid system
- For systems with both discrete and embedded GPUs, such as an APU and a Radeon Card
- Allows for automatic loading of both GPUs simultaneously for appropriate applications
- Cool, but I've already loaded separate OpenCL kernels simultaneously on both GTX 670 and Intel HD 4000 in Windows 7. Admittedly, it would be nice if it were officially supported functionality, though.
Choice in YUV format ranges, studio or extended, for Microsoft Media Foundation (MMF)
- Formerly, MMF video processing assumed 16-235 black-white, which professional studios use.
- Webcam and Point-and-Shoot use 0-255 (a full byte), which are now processed properly.
Wireless Display (Miracast)
- Attach your PC wirelessly to a Miracast display adapter attached to TV by HDMI, or whatever.
Multiplane overlay support
- Allows GPU to perform complicated compositing, such as video over a website.
- If it's the same as proposed for Linux, will also allow translucency.
AMD's advertised enhancements for Windows 8.1 are:
- Already covered, a part of WDDM 1.3.
48 Hz Dynamic Refresh rates for Video Playback
- Not a clue, unless it is part of an upcoming HFR format for consumers.
Aggressive V-sync interrupt optimization
- Again, not a clue, but it sounds like something to be Frame Rated?
Skype/Lync video conferencing acceleration
- … just when we move to a dual-machine Skype broadcasting setup…
DX 11.1 feature: Tiled Resources
- Some sources claim DirectX 11.2???
- Will render the most apparent details to a player with higher quality.
If you own Windows 8, you can check out 8.1 by downloading it from the Windows Store… if you dare. By tomorrow, Microsoft will provide ISO version for users to create install media for users who want to fresh-install to a, hopefully unimportant, machine.