NF8460M3 / NF8460M4: BMC VBATTERY Voltage Alarms

Problem and scope

After approximately two years of operation, the source’s servers showed a low-voltage alarm for VBATTERY, the motherboard CMOS/RTC battery, in BMC monitoring and logs. The article names NF8460M3, NF8460M4 and NF8460M4S. Although it introduces “two issues,” only this symptom is actually described.

English localization illustration of the historical BMC sensor list. The original crop contains sensor names and descriptions, but no measured voltage readings.

Firmware versions listed in the source

The vendor recommends updating the matching board’s BMC firmware. Its historical minimum versions are below; these are separate board-specific version branches, not interchangeable firmware packages.

Model	Motherboard PN	Motherboard name	BMC version listed by the source
NF8460M3	YZMB-00280-101	Motherboard_PRAGUE_I919598	>=4.24.0
	YZMB-00280-102	Motherboard__PRAGUE_I919598_102
NF8460M4	YZMB-00280-103	Motherboard_PRAGUE_I919598_103
NF8460M4/NF8460M4(DDR4)	YZCA-00588-101	Motherboard__Rome	>=4.1.0

The source’s short “low BMC voltage” cause label should not be confused with a measurement of the entire BMC power supply: its reported sensor and replacement criterion refer to the CMOS battery. The source gives no separate NF8460M4S motherboard row, so confirm that model’s board/firmware mapping with support.

Read the battery voltage after the update

The source states that the CMOS-battery sensor is no longer displayed in its BMC UI after the update. It supplies this model-specific raw command:

ipmitool -I lanplus -H <BMC_IP> -U <BMC_USER> -P <BMC_PASSWORD> raw 0x3a 0xb4

Sanitized explanatory illustration; substitute the configured BMC credentials. Its original example response is 02 06 41.

• var0 = 02: integer part.
• var1 = 06: first decimal digit.
• var2 = 41: ignored by the source’s decoding example.

The example is therefore 2.6 V. The vendor also calls for battery replacement when the measured CMOS-battery voltage is below 2.5 V. Follow the model’s battery-replacement procedure; a firmware change is not a substitute for replacing a genuinely depleted battery.