also just for the record or Google that is:
Installing Yosemite using Clover on P5N7A-VM with BIOS 519 and no external DSDT.
You have to use the I/O BIOS Block option. Executable Bit must be disabled or it will crash the moment XNU tries to say something. I assume I didn't need it before because the flashed Bios i had back then must have blocked that part so I wasn't aware (and it was in 2009 or something!). Drop the whole SSDT table, else crash acpi plattform.
For my CPU, Core2Quad Q8200, generating C and P-states didn't work, although Clover lists them with the right values, it only has 2 of each. Selecting the KernelPM patch enables it. No Null CPU needed. ACPI must be Patched. In regard to USB, it doesn't matter what is set in the Bios, I guess because the table gets dropped. Still not really happy with it (pain from the beginning with this board. I blame Asus.) Having the clock injected lets the System sleep, even in front of the installer. Wake up with power button all fine. But the USB won't work! Only selecting fix USB in the DSDT has USB working (sort of) but sleep and restart is now broken, I need to fix this. It must sleep else this thing uses way to much energy by todays standards.
Graphics is done with injecting nvidia, I only tested it with one Display but all outputs work (it should be able to do any 2 out of 3 if it is working right, I think it is)
Audio? Just use Voodoo. It is far superior to patching. It doesn't pop and it won't break. You even can adjust the amplifier. But the optical doesn't work, well that is a technology gone by anyway.