do I have a bad power supply?

April 22, 2009 at 01:48:00
Specs: Windows Vista
My computer randomly reset itself so I decided that it would be best to just power down while I was away at work.

I came home from work and the power in my office and an adjacent room was out completely as if something had tripped the breaker. I got the power in both rooms going once again, but now my computer won't turn on at all - no activity what so ever.

My first reaction is that the power supply went bad, but I'm not sure what happened considering I powered the system down before something strange happened while I was away for the day. Any suggestions / pieces of advice for me to follow to get the system up and working again?

See More: do I have a bad power supply?

Report •

April 22, 2009 at 02:00:08
Random resets are often a symptom of a failing power supply.

When you powered down did you leave the power lead still plugged into the mains and the computer. If so, then that is probably your problem.

Even though the computer is powered down the power supply is still live and and there is a small amount of current going to the motherboard. The only way to completely isolate he computer is to remove the power cord or in some case operates the small rocker switch at the back of the power supply that some power supplies have.

It seems that while you were out you had a power surge that tripped the breaker but before it did, it finished off your already dodgy power supply.

No harm in trying anew power supply. They are not expensive and relatively easy to fit.


Report •

April 22, 2009 at 04:49:02
First, make sure you have power at the wall outlet.

Also the sockets in wall outlets wear out, and are not a tight fit for anything that is plugged into them. If so, then the wall outlet needs replacing.
How PC Power Supplies Work

Report •

April 22, 2009 at 07:36:15
Opinions vary as to whether a PC should be left powered on 24/7 or shutdown at the end of the day. Regardless of your preference, you *should* have your PC, monitor, printer, etc plugged into a surge protector. Personally, I always shut my system down at nite, then kill the power at the surge protector.

If you determine your power supply needs replacing, do NOT buy a cheapie. You should expect to pay $40 or more for something decent. Corsair is currently one of the top rated PSU "manufacturers" around. I put that in quotes because they don't actually manufacturer PSUs. They have other manufacturers build them to their specs, then they slap on a Corsair label & sell them as their own. Antec does the same thing.

Report •

Related Solutions

April 22, 2009 at 08:35:04
Thank you all for the insightful responses, I appreciate it a lot.

I did have everything plugged into a surge protector, but I did not turn the surge protector off when I left for the day. I think I'm going to get another power supply and try that because after doing some other reading, I guess another symptom of a failing power supply is a lot of whining or droning sounds coming from the PSU which mine was definitely doing (odd considering I bought it two years ago; I thought they would last longer than that although it may have been a "cheapie" - was 80$ at Best Buy at the time).

Another concern I have after doing some reading is if my motherboard will be damaged at all or not. Would anybody know whether the chances are good or bad since the system was turned off (although the power feed to the PSU remains active) at the time?

Report •

April 22, 2009 at 12:19:31
First, the original power supply could have been defective or undersized months or even a year ago. And you could have seen the problem back then if using a multimeter. Same applies to finding what has failed before replacing the supply AND to confirm a new supply is sufficient. Price does not guarantee a sufficient supply. Multimeter reports imporant facts to even avert failures months later after the warranty expires.

Second, is the problem instead a power supply controller lockout? Another power 'system' component is a power supply controller. Its safety lockout circuit is reset when the power cord is removed for 2 or more seconds.

Third, whining more likely was a failing fan. That would have been a separate failure. But only you can provide information to better answer that.

Fourth, what defines quality? Supplies must perform numerous functions. When selling supplies separately to computer assemblers (who typically do not know how electricity works), these supplies can 'forget' to include essential functions. Therefore increase profits. Is your supply sufficient? To sell a supply missing essential functions, they must also 'forget' to include a full page of numeric specs. That full page is a manufacturer claiming (in writing) that his supply contains those functions that all computers require.

Fifth, can a supply damage a computer? That is one of the so many required functions. A supply must never damage any other computer parts. And nothing in a computer should damage a supply. Did they 'forget' to include those functions to increase profits? If it does not include that long list of numeric specs, a responsible computers assembler avoids it. But most computer assemblers buy only on price and watts meaning many supplies are missing essential functions.

Sixth, leaving a computer on to protect it is bogus. No, this was not even a controversy. But many computer assemblers heard the myth; then automatically believe it. If leaving a computer on has advantages, then we do same for every TV and radio. If true, then radios and TVs would also come without any power switch. Turn it off when done. That is best for the machine. But then notice which one is answering with so many technical details. This answer comes from generations of professional knowledge.

Seventh - surge protector did nothing useful when the protector was too close to electronics and too far from earth ground. Have doubts? Then post manufacturer specs that define each type of surge with numbers for that protection. Notice - it does not even claim to protect from typically destructive surges. Any facility that needs surge protection (ie your telco CO) does not use power strip protectors. They need effective protectors. They use protectors that are part of a surge protection 'system'. A surge protector and surge protection are two different items. The former is a connecting device to the latter. You computer adjacent protector is not connected to protection ... which explains why it does not even claim to provide protection.

Don't take my word. View it yourself. View those numeric specs that define protection. Notice - no such specs exist.

View that full page power supply specifications. Numbers that define surge protection already inside a minimally acceptable supply.

Report •

Ask Question