I just did a bit of research, and managed to compile netkas' PC EFI v10.5 to work with P55 boards. It was rather easy- it was 1 line of code changed in the freq_detect.c file.
I just updated tonymacx86-snowleopard.zip with the boot file.
This solves the 'system running too fast' issue, that was previously solved by a modified i5boot. PC EFI 10.5 is the latest and greatest Chameleon variant with many fixes and features not included in the official Chameleon RC3 release. For more information check out netkas' blog.
This change shouldn't affect my guides at all, and it will enable ATI users to use GraphicsEnabler=y boot flag to enable their cards! The fix also works for most nVidia cards. I updated the zip file to include this flag by default- now there is no need for NVEnabler 64.kext unless you're having issues with TV-out. I am still testing this issue, and will update the guide accordingly.
How to compile a patched Chameleon boot file for P55 boards.
EDIT: This guide is no longer necessary, as Chameleon RC4 now supports this fix by default.
1. Download any Chameleon source.
2. Open the folder i386/libsaio, and the file freq_detect.c in TextEdit
3. Type Command-F and find the word Nehalem
4. Delete this line of code:
if (cpu_family == 0x06 && cpu_model == 0x1a)
5. Add this line of code:
if (cpu_family == 0x06 && (cpu_model == 0x1a || cpu_model == 0x1e))
6. Open Applications/Utilities/Terminal
7. Open path to Chameleon folder
8. Type make clean
9. Type make embedtheme
10. If it compiled correctly, your patched boot file will be located in /sym/i386 :)