> One of T1000's has started displaying the following error message:
>
> VOLTAGE_SENSOR at MB/V_+3V3STBY has exceeded low warning threshold.
>
> What is this? The battery on the motherboard? I haven't been able
> to find it documented anywhere.
IIRC, it is an issue with the PSU. Check with Sun (hopefully you have a
support contract), there was an early batch of PSUs + MB combo that could
result in this. A shut down normally follows.