Short power loss, one system fine other frozen, why?

[elkinm]

I have two of my systems in the same room, three but third one does not have a monitor.

I had a very brief power loss. I noticed the house lights flicker but my clock was not even reset.

Afterwards one system my old and trusty AMD 1600+, MSI K7N2-L, 512 ram, 80+ GB ect. is fine connected to a 17" monitor which was sleeping at the time. Moving mouse, monitor starts and system works.
The main system AMD 2200 MHz, ABIT NF7-S 2.0, 1 GB ram, 80 GB HD ect. is not working, its 17 monitor was also sleeping but it was non responsive with the move a mouse.
Also I heard a strange slow beep, beep sound, like the sound that a truck or garbage truck would make backing up but it was quiet like the sound was coming from outside with windows closed. Well the sound was coming from somewhere around the system. And stopped when I turned it off.

When I turned it on, the Power and HD LEDs turned on but nothing happened. So I waited a few minutes and started again and everything is fine.

So the question is why did one die but the other one was working and what was that sound?

Thanks

 

[sandorski]

Don't know for sure, but similar things happen here(4 PCs, mine usually keeps running, but others often reboot or power down completely). I think it has to do with quality of Power Supply, though quality of motherboard may also make a difference.

 

[3chordcharlie]

Swap the PSU in from the working system temporarily. If it still doesn't work, come back and hopefuly there will be some more advice.

 

[thorin]

Originally posted by: sandorski
Don't know for sure, but similar things happen here(4 PCs, mine usually keeps running, but others often reboot or power down completely). I think it has to do with quality of Power Supply, though quality of motherboard may also make a difference.

All of that plus the quality of the Surge Supressor/PowerBar you have them connected to.

Thorin

 

[elkinm]

My guess was the PSU. The one that was up has a 300 Lite-On server PSU from a hot deal a while ago, while the other one has a Powmax 400 which measures very stable voltages. My guess is that the Lite-On could power the system from it's capacitors for that fraction of a second and the Powmax could not. Strange thing is that all the systems stayed on the entire time. Both systems are connected to regular surge protectors. I have not got around to hooking up my battery backup, maybe I should.

Would a PSU normally make noise if there is a problem or would that be a power supply. I did not check the 3'rd system, (which has an ancient 300 W PSU from another hot deal), but will when I get home.

And the system does work fine now after I gave it a few minutes to rest.