OK, i have a few suggestions:
1- Do you have your chipset drivers installed or up to date?
2- Tried a different pci-e slot?
3- Check if there's an update for you bios?
4- Try with another PSU? do this with suggestion number 2 if possible.
5- Try disabling driver signature
? as it appears to be a driver issue maybe, press f8 before windows boot logo and pick the 7th option.
6- If all fails try updating windows to the latest version you can and then do a fresh driver install.
Edit:
7- Check if your .net framework/visual c++ are updated too, if not, you can install the ones that came with the driver package and access them where the installer extracted them, you can cut/paste those out the extracted folder to skip them while installing the display driver itself to save some time
.
"Windows's HDD":\AMD\AMD-Catalyst-whatever.version.you.have\Packages\Apps <-- The folder where you'll find the stuff installed by amd's installer.