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z390-e STRIX VCCIO + VCCSA Voltages

Level 9
Does anyone know why the bios would override manual inputs for these voltages? See pics below.

I've dialed in stable CPU and memory overclocks. OCCT for system stability and HCI MemtestPro for memory stability (400% coverage with current 17-19-19-39 @ 4133mhz, testing 30 of 32gb available). CPU is a 9700k, 5.1ghz all cores, 48 uncore.

I've been playing around with voltages and discovered some weird things happen when they are too low or high.

Too low VCCIO/SA voltages result in higher core temps 2-4ºC, memtest initializing slower and not testing all available RAM.
Setting voltages to to 1.25v and the BIOS runs them at 1.28v, which appear to be too high imo.
Manual inputs of 1.24v override to 1.24375 but actually run at 1.264v. Believe it or not, cores actual run several degrees cooler with these higher voltages, and memtest runs quicker, utilizing available memory.

Any experts willing to chime in?


Super Moderator

The UEFI is not overiding them, it's simply how it's being interpreted depending on how and where the voltage is being read from.

You can safely volt these rails up to 1.3 so set a value that works best for stability. As these are signal rails, sometimes too much voltage can be detrmental to stability - so test methodically.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090