We have a HP ProLiant ML350 G6 server causing us a few problems.
The main symptom was that every so often we would find the server simply powered off. We turned the machine back on and investigated to find that one of the PSU fans had started whistling and blowing a lot of air out of the back of the server. At the same time, we noticed a flashing amber light on the front of the machine:
Presuming that our PSUs were at fault, we replaced them both. The system started up fine and everything seemed to be working OK. No amber light, no whistling or excessive blowing.
However, less than 24 hours later, we've got a repeat of exactly the same symptoms. The machine hasn't actually turned itself off this time but the amber light is back, as is the whistling.
We then took the side panel off to investigate the problem further and found that LED in position 2 on the motherboard (PSU 2) has a solid amber LED.
We have had a look at HP SystemManager but this simply says that our system is fully healthy - no component problems.
What else could the problem be if not the PSUs?