I also have a Z800. I've been trying to install 4.0-rc4. The installer tells me that the following features are missing:
I have a ticket open on the HP support forum asking for help. Someone helpfully suggested a few BIOS settings that I might try, but I have not been having any luck.
Might anyone here have any suggestions?
One other clue: Someone on the HP support forum suggested that the problem might be related to the x58 chipset and sent me a link to a data sheet:
I'll be reading that data sheet more closely later today, but my current impression is that solving the problem would take a BIOS patch. Or maybe the chip firmware can be flashed directly? But even if it could, the underlying instability might remain. I just don't know.