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Jean Delvare
7cc03f5029
2.6.9, the right VID conversion formula is selected automatically depending on the CPU model, so the user shouldn't have to care. git-svn-id: http://lm-sensors.org/svn/lm-sensors/branches/lm-sensors-3.0.0@4543 7894878c-1315-0410-8ee3-d5d059ff63e0
57 lines
2.0 KiB
Plaintext
57 lines
2.0 KiB
Plaintext
VID pin settings
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--------------------
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The VID (Voltage Identification) pins on sensor chips
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are used to read the CPU Core voltage setting.
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The VID setting can be controlled by jumpers on the board,
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or, in newer motherboards, by settings in the BIOS.
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On these newer boards, the BIOS programs some device's
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pins which in turn controls a DC-DC Converter to set its
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output to a certain voltage. These pins are also connected to
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the sensor chip so that the VID setting can be read back
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by applications.
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There are generally 5 VID pins. Recent motherboards may use 6 pins.
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The VID codes are defined by Intel in documents titled
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"VRM X.X DC-DC Converter Design Guidelines".
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(VRM = Voltage Regulator Module), or
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"Voltage Regulator-Down (VRD) 10.0 Design Guide".
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These documents are available at http://developer.intel.com.
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There are several different VRM document versions.
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The common versions are as follows:
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Document Version Voltage Range Increment Processors
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---------------- ------------- --------- ----------
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"2.4" 0.8 - 1.55 0.025V AMD Opteron 24x
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8.2 (8.1, 8.3) 1.30 - 2.05V 0.05V PII, PIII, Celeron
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2.1 - 3.5V 0.10V
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8.4 1.30 - 2.05V 0.05V PIII, Celeron
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4 pins only
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8.5 1.050 - 1.825V 0.05V PIII-S Tualatin
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9.0, (9.1) 1.100 - 1.850V 0.025V P4, AMD Socket A
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10.0 0.8375 - 1.6000 0.0125V Desktop Socket 478
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"2.4" is not an actual document version but simply a way to identify
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AMD Opteron 24x processors.
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Note that versions 8.1 - 8.4 are compatible.
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Since Linux 2.6.9, the correct VRM version is selected automatically
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based on the CPU brand and model. Thus you shouldn't have to care about
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it. If you are using a brand new CPU and even the latest kernel complains
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("Unknown VRM version of your CPU"), this means that the kernel must be
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taught about this new CPU model. Please report to us in this case.
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Remember, the VID pins on the sensor chips are inputs only.
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You cannot use them to manipulate the actual processor core voltage.
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------------------
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Copyright (c) 2002-2004 Mark D. Studebaker
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