I would reccomend to change the “Turbo boost power max” to 9 watt (more won’t do anything, it’s just how much power the CPU may use. The 8100Y is limited to 9 watt. So if you use in XTU a limit of 15 watt, the chip will still use its own limit).
Then you can start to play around with the “Core voltage offset”. Set it to -50 mV, the run some stress tests (Futuremark stress test, play a videogame, run some random benchmarks or use the stress test of XTU itself). If the laptop doesn’t crash, increase the voltage offset with 10 mV (from -50 to -60 mV) and repeat the stress test.
At some point the laptop will crash and restart. No worries, nothing is broken Then start XTU, set the “Turbo boost power” again to 9 watt, and set the "Core voltage offset 5 mV higher than what made the Minibook crash (if it crashed at -80 mV, try -75 mV) and repeat the stress test.
If you’ve find a stable offset (like -75 mV), increase it with 5 mV (-70 mV) and use that as final setting. Save it as a profile in XTU as sometimes (after a restart) the power settings re reset to their default values.
If for any reason the Minibook is crashing randomly, then increase again the value with 5 mV.
Pay attention to set the ‘Core Ofset voltage’ to a negative value (like -0.040V) and not a positive value. (like 0.040V) So slide to the left
I’m using an undervoltage of -70 mV as -75 is stable, and -80 isn’t. In benchmarking I got a 5-10% increment in cpu score.