...i have the same issues @ 1800+. With latest bios no issues @ 1800 CL12-17-17-28-1T for me, but higher 55 error code as you. For 3d perhaps it's enought, but for 2D as XTU no.
...yes, your advise is true bro ! I should try to know how my cpu can do. Light 3D over 6.2 GHZ is good if CASCADE can cooler the cpu ! Are you happy of your M8H ? With mem over 1820 CL12 i have issues, but i haven't try last bios yet