Power Supply Issues?

  br8nd4n 07:28 17 Mar 2008


Firstly I'm not very technically minded, so apologies up front for that, but I hope someone who does know what they're talking about can help.

I have a Legend 2.5 Pentium 4 that has served me well for a few years now. The problem I have is that out of the blue the power on/off button is not starting up the computer. If you pull the main plug out of the wall and fiddle with the fuse before putting it back in the wall the computer does power up and when pressing and holding the power on/of button on the front of the PC when on it does switch off suggetsing its not simply the switch. I have replaced the power lead and fuse to eliminate that problem too. All the cooling fans are spinning fine inside. I haven't upgraded any hardwear and the cover hasn't been off the unit recently so I don't think anything has been unseated inside or wires come loose.

Any suggestions? All help would be grately appreciated.

Thank you in advance!

  Gongoozler 07:51 17 Mar 2008

You say that the fans are spinning. Is this when the computer fails to start or only when it has started correctly?

The computer starting up involves the power on/off switch, the motherboard and the power supply. You have eliminated the switch, so that leaves the other two. telling which one is almost impossible other than by substitution. When the computer is off there is still 5V standby power applied to the motherboard by the PSU, and this is what is used to start the computer. I suspect that when you "pull the main plug out of the wall and fiddle with the fuse" you are just removing the 5V standby and for some reason this lets the computer restart. I suggest that you buy or borrow another PSU and see if that cures the problem. A PSU isn't terribly expensive and is fairly simple to replace. A new motherboard is another matter entirely.

  br8nd4n 08:00 17 Mar 2008


Thank you for your prompt response. The fans are only spinning when it has started correctly.

I'm going to try the PSU replacement option first. Is it best to swap it for a like-for-like unit i.e. same make, model as I currently have? On the side of the PSU it says "FSP Group Inc" and is 250W, 115/230V.

Thanks again for your advice. Very helpful.

  Diodorus Siculus 08:11 17 Mar 2008

Get a PSU with a similar physical size and increase the wattage to, say, 350W will be your best bet. Just ensure that it is the correct one for your mobo. The last one I got was modular and so allowed me to leave out the cables that were unncessary.

  Gongoozler 10:14 17 Mar 2008

You are unlikely to find a PSU of less than 300W rating, and you will find the price ranges from under £10 to over £100. I have been using a PSU for about 4 years that I bought from Ebuyer and cost about £10. More expensive PSU's tend to have quieter fans and have better regulated voltages which can be important in high performance computers. Any ATX supply should fit your computer. Have a look at some of these from Ebuyer click here. A very useful feature of the Ebuyer site is the Customer Reviews.

  br8nd4n 10:17 18 Mar 2008

Thanks very much for your help. I've ordered a 450W PSU online. Very grateful for your advice.

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