Nice investigation.

But I got lost somewhere when you say that for instance 100 -> 120 Mhz and not 100 -> 233 Mhz. How can you be so sure of this?

If I understood it right the 3632 Tref setting is in fact a 1872 value (3632= 120mhz -> 1872) and it's the bios who label it wrongly. Is that what you mean? I can't see why will they label it in this way.

(If I got it right) According to you theory, the Tref of 0064 is in fact 2808. How can you explain the fact that this setting is extremely slow and even freezes several people's systems?