PC suddenly shuts down!

[92star]

Hi,

I recently upgraded my old AMD K6 powered PC for my parents to replace their very old PC so they can access the net properly. I replaced the complete mobo with an AMD Sempron 1.5GHz CPU on a Gigabyte mobo (used/working off ebay), put in a brand new 160GB hard drive and DVD drive and utilised the existing case and PSU. At first everything was running fine. Using XP SP2 and AVG anti virus, internet access was good and all programs were functioning correctly.

After a while I purchased an AMD Sempron 2.0 GHz (again off ebay) to give everything a bit more speed. The CPU worked O.K. to start with then but then after a short while, the PC suddenly shut down. As it shut down, a two-tone beeping sound came from the case speaker. The best way to describe the sound was that it sounded like an old style police siren. This lasted for about a second or two before everything shut down. Thinking the 2.0 GHz CPU may be faulty, I put the original 1.5 GHz CPU that came with the mobo back in.

The PC then worked fine for several weeks until the other day when it suddenly shut down again accompanied by the same two-tone beeping sound. I turned off the updates for XP and the AVG anti virus and this seemed to do the trick for a couple of days but now it keeps shutting down on a regular basis. If it is left for a while, I can use it for several minutes before it shuts down. If I restart it straight away after a shut down, it will usually shut down again before the login window appears.

I am a bit puzzled as to what is causing this problem and given that this upgrade did not cost me too much money, I don't particularly want to take it somewhere and end up shelling out more than the upgrade cost to have it put right. I am reasonably competent with computers and would be very grateful if anybody could throw a few suggestions my way that I can try.

Thank you in anticipation.

[Gatto]

Hey 92star,

I'm surprised you went to all the trouble of changing mobo/cpu/hdd! There are a couple of issues that I can see causing the computer to shut down of its own accord - temperature and lack of power.

The PSU has operated well for a while, before all the upgrades. It may be that they are requiring more power than the PSU can provide - especially if it was a cheap one to begin with. What is its rating?

Also, with all the upgrades, more powerful components are going to churn out more heat. But, with a Sempron 2Ghz I don't see that being an issue. All the same, given the time differences and the fact that keeping it off for longer will keep it going for longer leads me to this being an issue.

What is the make/model of the mobo - this may give a clue as to what the beeps mean.

G

[92star]

Hi Gatto,

Thanks for the reply. I did the upgrade as a project just to prove to myself I could do it (I'm an engineer by trade so I like messing with things!). I thought temperature might be the problem but the heatsink fan works O.K. and I'd put in an extra fan that uses a PCI slot at the back which really pushes out some air. I was concerned that the new components would put out a lot more heat and the case which is 11 years old has virtually no natural venting slots.

The motherboard is a Gigabyte 7VT600P-RZ and the PSU is the original unit which is rated at 235W. I can remember at the time when I did the upgrade mulling over whether to upgrade the PSU or not.

Hope this is of some use to you.

Cheers.

[Chris]

** Topic Moved to:
** Hardware --> Motherboards/CPU/RAM


I've looked up the standard beep codes, which one best fits?

No Beeps Short, No power, Bad CPU/MB, Loose Peripherals
One Beep Everything is normal and Computer POSTed fine
Two Beeps POST/CMOS Error
One Long Beep, One Short Beep Motherboard Problem
One Long Beep, Two Short Beeps Video Problem
One Long Beep, Three Short Beeps Video Problem
Three Long Beeps Keyboard Error
Repeated Long Beeps Memory Error
Continuous Hi-Lo Beeps CPU Overheating

I'm having doubts about the power being a problem as the Sempron needs 45W, hdd will probably want about 20W, so unless you have a big graphics card or are overclocking the processor then 200W should be enough.


[Edited on 25-4-2008 by Chris]

[Gatto]

Two beeps could then be either a POST or a mobo problem. As the computer starts up correctly, then it must be mobo. This could be either a faulty mobo or power, i still lean towards power. But, is the mobo still under warranty?

G

[Chris]

Of course, it could be a duff mobo battery. Try replacing that if all else fails (should be watch battery sized)