4. STRESS TEST THE CPU
failing the stability tests at 3.9GHz but was doing fine at 3.8GHz, you'd be stuck at the latter speed, without knowing if you could actually reach a higher value between the two speeds.
By adding reference clock tweaking to your overclocking tool belt, you can now begin to test the actual limits of your CPU. It's then a matter of some simple math to find the right value combinations to achieve the clock speed you want to test out.
However, because the reference clock is tied to other values throughout the system like memory speeds, increasing it could possibly introduce other instabilities that would make it difficult to single out the cause of crashes. As a result, we'd recommend being extremely conservative in your base clock tweaks – no more than a few MHz above default, especially if your notebook isn't a water-cooled beast like the GX700. We use Cinebench R15 as a quick way to test the stability of an overclock. It stresses all the CPU cores, so if your overclock isn't stable, your notebook will most likely freeze or restart. Intel XTU also comes with a built-in stress test that works better for assessing long-term stability. Just check the box for the CPU Stress Test and select the duration for which you want to run the test (the longest possible is a whopping 30 days). If you think you've hit a stable value, you may want to set it to run for an hour for starters.