1. Try obtaining crystal clock frequency from CPUID_TIME_STAMP_COUNTER (15h) leaf from ECX.
  2. On failure, take predefined values for known processor models.
  3. On failure, check for CPUID_PROCESSOR_FREQUENCY availability and divide by the TSC ratio.
  4. On failure, assume 24 MHz.

Added info about the highest supported leaf (OC_CPU_INFO::MaxId).
Fixed a few places which were incorrectly comparing standard CPUID leaves against the maximum extended function leaf (OC_CPU_INFO::MaxExtId).
Add a warning in case the TSC- and ART-derived frequency calculations are wildly different.