...
At close to max overclocking, temperature and heat will reduce or "eat" into the CPU speed. The reason is electron mobility is reduced at higher temperature. Below the break-even point, heat will "eat" into less than 50% of intrinsic the CPU frequency increase (by Vcore increase). Above the break-even point, heat will "eat" into more than 50% of the intrinsice CPU frequency increase.
E.g. only for illustration (exact number may vary)
Some where below 2400 MHz, 25 mV would increase CPU frequency by 20 MHz, this is after the heat has "eaten" 5 MHz. Intrinsic frequency increase would be 25 MHz.
At 2400 MHz, 25 mV would increase CPU frequency by 12.5 MHz, this is after the heat has "eaten" 12.5 MHz, otherwise one would get 25 MHz increase had heat was completely removed. So 2400 MHz is the break-even point, or point of diminishing return on frequency.
Some where above 2400 MHz, 25 mV would increase CPU frequency by 5 MHz, this is after the heat has "eaten" 20 MHz, otherwise one would get 25 MHz increase had heat was completely removed.
The above scenario shows how overclocking will eventually come to a halt, from 20 MHz increase to 12.5 MHz increase to only 5 MHz increase for each step of 25 mV increase in Vcore.
At the start, find out the stable CPU clock freqency (f1) at full load at rated Vcore.
Increase Vcore by 25 mV, find out the stable CPU clock frequency (f2) at full load.
Based on these two numbers, 4 (f2 - f1) will approximate the ideal CPU frequency increase per 100 mV Vcore increase, since temperature increase is minimal.
This number should be around 120-140 MHz / 100 mV for Tbred B and Barton.
By combining clock frequency and temperature, the rule of thumb is:
- 10 MHz / C, at full load per 25 mV Vcore increase is about the break-even point for overclocking (point of diminishing return). 12 MHz / C for extreme cooling.
- Below 10 MHz / C is "easy" and economical for overclocking. 12 MHz / C for extreme cooling.
- Above 10 MHz / C becomes harder and harder to overclock. 12 MHz / C for extreme cooling.
- And 2-3 MHz / C at full load is the limit.
