[coreboot] ASRock E350M1: How to set RAM voltages under coreboot?

David Hubbard david.c.hubbard+coreboot at gmail.com
Sun Apr 21 20:22:15 CEST 2013

On Sun, Apr 21, 2013 at 5:43 AM, Rudolf Marek <r.marek at assembler.cz> wrote:

> In the long term, would it be possible to do this stuff from the OS,
>> not some bios setup screen? Or is it too late by the time the OS is
>> booted? On the SiS 630 we controlled overclocking parameters via a
>> user mode command once Linux had booted, but that was long ago ... do
>> the new chips make this easier, or harder?
> Yes sounds like good idea (to have it in nvram) but only as option. My
> DDR3 memory does not work well on 1.5V (it has to have 1.65V) from the
> start.

The memory voltage can be automatically detected from the SPD -

The SPD logic is in AGESA, I don't know exactly how to get the voltage
parameters out of it, but AGESA does not change the voltage, it just uses
SPD to set the timings.

Configuring the voltage in nvram would still be useful if the user is
undervolting to save power or maybe overclocking in the future.

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