Dell PowerEdge SC1425 – Fan control

If you are concerned about the fan speed (and noise) consider this. On my Poweredge 2500, the only way I've found to control the fan speed is to adjust the temperature thresholds. If the maximum temperature is too close to the current reading, the fan spins faster trying to cool it off. When you raise the maximum temperature, the fan relaxes. So check to see if your thresholds are set too low.

Of course, if your thresholds aren't set too low, then you have a separate issue regarding cooling.

Well, you've actually got a lot of good information.

• First, you know that the problem doesn't affect a running system assuming it runs for extended periods of time without issue (e.g. weeks). You might double-check that with tools designed to stress your system (cpuburn or the like), but let's take it as read for now.
• Second, you know that the problem does prevent booting.
• Third, you know that the problem reliably goes away with time.

What that tells me is that there is something that is true immediately after the system shuts down that is not true 1-24 hours after shutdown. Also, that fact only matters when the system is booting.

My first thought is heat, but there are some tests that you don't mention doing:

• In case the problem is some electrical state remaining in the computer, I would try unplugging the power, and then holding the power button in for 10-20 seconds.
  • It takes a little while for the last remaining charge to bleed off, possibly 1-24 hours.
  • If you listen and watch very carefully, you can probably hear a fan start to spin up, or an LED light and then dim to off when you do this.
  • You're more likely to see the above if you do this with the cover off.
  • If the problem remains, it is not a simple case of some critical value in memory failing to clear.
• The other test I suggest is to boot the system to full operational status, and then immediately shut down (no more than 5 minutes on) and see if the system will restart successfully.
  • If it restarts, you know that the problem takes some time to build (my first thought would be heat at this point)
  • If it doesn't restart, you know that the issue is triggered almost immediately. You can restart at different points during the POST to narrow it down, but ...

I have seen systems that will not reliably recognize the RAM in the system. If this happens and results in no RAM... well, I would expect more booting to occur than you describe, but I wouldn't bet my life on it.