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I have an HP Pavilion Elite desktop computer, model HPE-490t. I like it because it didn’t cost too much, boots itself from an SSD, came with 16 GB of RAM, and has six CPU cores for editing video and camera RAW images. It has one behavioral quirk that I cannot explain, however. The recent power interruptions here in the Northeastern United States got the machine into a state where it could not be restarted. It would power up for a second or two, shut down, and then power up again, never being able to get to the point of showing anything on the monitor.
I unplugged it for about 10 seconds and plugged it back in. Same behavior (fails to boot).
I unplugged it and walked away for an hour, then plugged it back in and it worked perfectly!
I think something similar happened after installing a second hard disk drive into this machine.
Why does the computer behave differently depending on how long it has been unplugged? Where is energy stored that affects the machine’s ability to boot? Capacitors in the power supply? Battery on the motherboard (there is one for the clock, but that wouldn’t be exhausted by being unplugged for an hour, I don’t think)?
1Does it still behave this way after being unplugged for an hour? In other words, does unplugging it for an hour fix the problem? From what you've said it sounds like the problem went away. – CharlieRB – 2011-11-22T17:57:38.967
1Sounds like an overheated CPU. – Andrew Schulman – 2011-11-22T17:49:12.070
Cold boot problems can be caused by finicky hardware that works only when warmed up. For example my RAM will give millions of errors in memtest when cold, but runs stable when warm. However, this is admittedly due to overclocking. It's much less likely to happen in a stock system, so probably isn't your issue, but just thought I'd mention it anyway. Also, look into any reported issues with your SSD, as some of those are notoriously fickle. – Igby Largeman – 2011-12-07T19:47:41.270