There were times when real and strict enginering rules were applied, that meant
10% voltage margin and also 10% frequency margin, so the higher binned chips still had 10% higher frequency capability while being more or less stable.
With 1-2GHz CPUs this amounted to a mere 100-200MHz frequency uplift for the most expensive part, sometime a little more and those 10% were left to the overclockers at their own risks, nowadays with 5GHz+ CPUs 10% is a lot of megahertz and both Intel and AMD started to grab this margin, it could work or it couldnt when the last % margin is moneyed for a few bucks more.
10% voltage margin and also 10% frequency margin, so the higher binned chips still had 10% higher frequency capability while being more or less stable.
With 1-2GHz CPUs this amounted to a mere 100-200MHz frequency uplift for the most expensive part, sometime a little more and those 10% were left to the overclockers at their own risks, nowadays with 5GHz+ CPUs 10% is a lot of megahertz and both Intel and AMD started to grab this margin, it could work or it couldnt when the last % margin is moneyed for a few bucks more.