It seems that the i2c bus has somehow been screwed up into returning all ones for everything on this board. I am still not sure what causes it, and nothing shows up in dmesg or the syslog. This is using a piix4 i2c controller. Is there any way to reset the i2c bus manually? Do you have any insight on what could be causing these problems? The following are the relevant bits from a sensors call on a board on which it seems the i2c bus has been pooched: ds1780-i2c-0-2f Adapter: SMBus PIIX4 adapter at 1040 Algorithm: Non-I2C SMBus adapter V_CPU: +3.32 V (min = +3.32 V, max = +3.32 V) ALARM VTT: +3.58 V (min = +3.58 V, max = +3.58 V) ALARM 3.3V: +4.38 V (min = +4.38 V, max = +4.38 V) ALARM 5V: +6.64 V (min = +6.64 V, max = +6.64 V) ALARM 12V: +15.93 V (min = +15.93 V, max = +15.93 V) ALARM -12V: -4.79 V (min = -4.79 V, max = -4.79 V) ALARM temp: -0.5?C (limit = -1?C, hysteresis = -1?C) ALARM adm1021-i2c-0-4e Adapter: SMBus PIIX4 adapter at 1040 Algorithm: Non-I2C SMBus adapter temp: -1?C (min = -1?C, max = -1?C)ALARM (LOW,HIGH) remote_temp: -1?C (min = -1?C, max = -1?C)ALARM (N/A,LOW) die_code: 255 And the same from a normal board (same model): ds1780-i2c-0-2f Adapter: SMBus PIIX4 adapter at 1040 Algorithm: Non-I2C SMBus adapter V_CPU: +1.49 V (min = +1.38 V, max = +1.58 V) VTT: +1.49 V (min = +1.37 V, max = +1.58 V) 3.3V: +3.24 V (min = +2.93 V, max = +3.59 V) 5V: +4.97 V (min = +4.45 V, max = +5.44 V) 12V: +12.06 V (min = +10.68 V, max = +13.06 V) -12V: -12.65 V (min = -13.68 V, max = -10.58 V) temp: +35.0?C (limit = +45?C, hysteresis = +40?C) adm1021-i2c-0-4e Adapter: SMBus PIIX4 adapter at 1040 Algorithm: Non-I2C SMBus adapter temp: +41?C (min = +20?C, max = +80?C) remote_temp: +34?C (min = +20?C, max = +44?C) die_code: 5