Don't bother about the BIOS modification I can do that but care about the "hardware level" disableing. The fuse values whisper me all that information (CONFIG_DIE_FUSES 0xFFF33FFF) 3 means that only 2 pipe quads in that core can work. Usually on X800VE you can find not 3 but 1 there - which definitely means 1 quad.
The number of the active pipes (in BIOS) can be changed usind BIOS editor (RaBit only shows the number of the pipes).
So if I have 0xFFF33FFF, I'll never have something better than 8 pipes (2 pipes quad) ?
Linking the second bridge could perhaps change it into 0xFFF37FFF, no ?