Take a look at the main Windows 8 RTM Thread, they write something about it. I also had many problems with the installation. Nevertheless, after installation the OS was giving me BSODs all the time - nothing helped. Now using Windows 7 and all works just fine. Pozdrowienia dla Czech!
Back to my original opinion of using a VHD to try installing. If it installs into a vhd, we know it is the upgrade at fault, if it cannot install into a vhd either, it is the hardware. Only need about 15GB free space to install W8 in a VHD.
Sounds something is busy, did you run the iso from inside Windows when this occurred? Became thinking of the CPU as a workaround, maybe helps decrease to just a minimum of active cores during install.
I have an amd sb950 controller on an asus m5a99x evo, with 7, i have to partition, reboot, install loading my Ahci driver, if I don't do that my disk 0 becomes 1, and 1 goes 0 I installed 8 without loading any driver and then i updated manually via device manager to the amd "Sata Ahci" driver. I tried raid mode and raid mode goes well did set raid Uefi driver mode in bios it happened with my old gigabyte 785gmt too, sb750 chipset hope this helps
I have followed the Howtogeek guide up to sending bcdboot command, got this error: Code: C:\>bcdboot.exe W:\Windows BFSVC: BcdOpenSystemStore failed with unexpected error code, Status = [c0000098] C:\> Btw. I generated my ISO md5sum with this result: 7a10316a79a543f2bf4953a4332b4323 *Windows_8_Pro_EN-US_x64.ISO and also attached the checksums of the unpacked root used for installation, if anybody cared to verify.