start up trouble - please help!

Right...basically I need your help to work out what component needs replacing in my desktop!

I was in the middle of surfing the net and there was a 'pop', the computer went dead. I tried to turn it back on - the bios started up and displayed on the monitor, then the computer turned itself off again.

However now every time I try to turn on the computer the monitor does not display anything at all. The case fans, cpu fan and AGP fan all start up, and the motherboard beeps once, but nothing displays on the monitor. Also the HDD does not appear to start up and the optical drives do not function...

I have looked at the cpu, motherboard and graphics card - nothing looks fried. I think it's either the AGP or motherboard, because if it was anything else I should at least be able to see the bios start up. Any thoughts guys???

Pentium4 3.2Ghz Prescott
Radeon 800Xpro 256Mb
4 answers Last reply
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  1. This is always tricky territory for forums. People like to help but dont want to give bad advice as it can be many things. So you wont get a reply with change XYZed component and if you do, its foolish.

    First thing to do is basic troubleshooting from the ground up.

    BIOS displayed or splash screen? What i mean is, did it look like a normal boot then just turn off?

    Considering the behavior you stated about fans spinning and some drives working, give the Power Supply a smell at the exhaust fan. Smell like you just lit off some fireworks?

    If one set of drives is kinda working and others not, it could likely be that the power supply kicked the bucket. but its a good place to start.

    If you have other parts available, start with a tear down to all basic components required to start. PSU, MDB, CPU, RAM (and video if not on board) and see what the result is.

    The hard part about this is that you dont want to do additional damage to any components...and there is no guarantee that a failure of that nature did not do any initial damage.

    Good luck...been there...pop reboot fail, smell power supply.

    //-No warranty implied or expressed-//
  2. First thing to do is remove everything. Presuming you have onboard video and audio, remove any NIC card, video cards and audio cards. Leave a stick of ram in (and if it still doesn't work, switch that with the stick you took out just to see if that's the problem). This will help you narrow things down to board/cpu/psu versus any of your cards straight off. If things work, start adding one component back at a time until things stop working again. If things don't work, consider testing them in another machine. It's unlikely that a bad card is going to cause damage to another machine.

    It's really just a process of elimination. Keep track of what you have tested and can rule out each step of the way. Having a second machine (or at least a spare motherboard and PSU around sitting on a table) can make this process far more efficient.
  3. Thanks fo the ideas guys.

    There was a slight burning smell after it turned itself off the first time, but I couldn't locate where that was coming from as it didn't last long.

    I dont think the power supply is the problem as I have had PSU problems before - either nothing at all turns on, or just some of the molex connectors dont work. I've unplugged all the molex connectors from the case fans and then changed all the connectors around to the AGP, HDD and optical drives, but still the same symptoms persist. AGP fan starts, CPU fan starts and motherboard light comes on, but no HDD or optical devices come alive! So it's not the molex connectors.

    The first time I tried to turn it back on it came up it was the splash screen, and then it turned off. I didn't realise that was different to the bios starting up. Any more ideas??
  4. Sounds a bit like the old capacitor issue could be the cause. Check all the capacitors on your mainboard, especially near the power coils next to the cpu.

    The top of the capcitors should be totally flat with no leakage. If even one is slightly raised or leaking it can cause this problem.

    If this is the problem, check the rating of the faulty capacitors and replace them. It is simply a matter of unsoldering and resoldering on the new ones. But make sure you put them on the right way (ie the same way they were).
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