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Maximum Efficiency: Build A 25W Performance PC Using Core i5

Step 2: Undervolting

We decided to tweak the CPU core voltage and introduce a minor Vcore reduction to see if we could make another impact on power consumption. Experience tells us that a few percent voltage reduction typically doesn’t lead to stability issues. However, excessive undervolting can certainly be problematic, and insufficient voltage supply can be complex and tricky to identify. If you aren’t sure, we recommend staying close to the default voltage to avoid unneccessary issues.

MSI’s ControlCenter tells us that the default voltage for our test system is 0.95V (idle). CPU-Z confirms the setting and tells us that it’s effectively 0.944V.

We decided to adjust the voltage from 0.95V to 0.90V in the ControlCenter software.

The result was an effective CPU voltage of 0.888V at idle.

Load Vcore Readings

Peak Vcore at default auto settings.

Here's the peak Vcore at 0.9V manual setting.

We measured a decrease in system power at the reduced settings, but the impact was negligible at idle. At peak load, we had a decrease from 80W to 76W total system power.