Therefore, it would not be possible to use software for finding out about a processor's maximum clock rate. Most of the 233 and 266 processors, however, lack this feature. According to its own sources, Intel has only delivered Pentium II 266s with L2 ECC to a few selected server manufacturers. This significant difference allows us to expose fake Pentium II 300s. If the ECC function is missing, it is very likely that the processor is an overclocked 266.
Any relevant information is top secret.
Consequently, we had to make do without help from Intel. In this register, bit 5 determines whether ECC testing is enabled. However, querying this bit only does not help much, because some mother board BIOSes don't use ECC testing for the L2 cache even if it is available in the processor. This way, they trade in some operating stability for an increase in performance of about three percent. If ECC is enabled without ECC cache, the system will crash without warning.