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Fans start up but otherwise dead.

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nob1

Technical User
Mar 5, 2005
53
GB
My grandsons machine stopped in the middle of an online game and wouldn't reboot. The fans are running but there's nothing on the screen. I've isolated it from all its peripherals except keyboard and mouse to no avail so I changed the PSU which made no difference. It's a fairly recent machine with a 3GHz P4 on a Gigabyte MB, 2 SATA HD in RAID 0, 2Gbyte RAM. My question is:- what could stop the BIOS from starting up? Dead CPU? Dodgy RAM? HD problems? Motherboard? I'd be more than grateful for any help - I know you guys are good because you have helped me before
 
Well, you have tried a different power supply, right?
If you happen to have or can get hold of a digital multimeter then you can google a tutorial on how to test the power supply, that will for sure eliminate it as the problem. If not, then you can buy a tester of sorts from bestbuy or compusa for $10. They arent as good as a digital multimeter but better than nothing. They are called power supply testers. They will only tell you if they will turn on, still that is a help.
Re-set the bios but first check the manual for how to do so as some mobos are different. For most you unhook ALL sources of power, take out coin battery and move cmos jumper on the mobo from pins 1 and 2 to pins 2 and 3 for 5 minutes. Then put jumper back to pins 1 and 2, connect power and try to start computer. But check manual, some are different, like pc chips for instance. Some gigabyte mobos too.

Since you have disabled all but the most necessary can i also suggest you take the mobo and power supply out of the case? Mobo could be shorting on the case.
Also, the power\on switch could be bad so disconnect that. You can use a flat screwdriver and touch the screwdriver to the 2 pins that the power\on switch would normally be connected to. If the computer starts that way then the switch is bad. Since they only cost about 5 cents it would be no surprise there.
Take out all ram sticks except for one.
Take heatsink\fan\cpu apart and clean old thermal paste or thermal pad off and install new thermal paste and install hs\fan\cpu back onto mobo. Use credit card to clean off heatsink if there is a thermal pad on it.
Take ram out and gently clean the gold part with pencil eraser. Use can of air to clean out ram slots and general cleanup of mobo and fans. Dont let compressed air turn any fans as that can cause static buildup. Use small stick like a toothpick or whatever to hold the fan while you are applying canned air.
Try a different video card if you can. If onboard video then you may have to move a jumper.








Good advice + great people = tek-tips
 
Yes I had changed the PS - I have now changed the CPU as well. Still no joy! I followed some of your suggestions - Eliminating the Power On switch. Cleaned up the RAM & graphics card connectors done a general cleanup and something has changed. When I press the on button now, the fans start up and the internal speaker beeps constantly at high frequency with the power on LED flashing at the same frequency! I've rechecked all my connections and can't see anything wrong. I don't believe there is a MB to chassis short as the fault occurred when the machine was in use so have not tried isolating it. Any suggestions? What does the beeping mean? Your suggestions much appreciated.
 
Are you sure the monitor is working?

Most beep codes are described or can be found here

Its a pdf file - so right clicking and downloading may be preferred!
 
Off the top i think it could be a heat problem, but it could also be video or ram.
If a heat prob then its supposed to throttle down. i imagine you have the side of the case off, are there any airflow restrictions?

Is there a way for you to check the ram on another computer?
Same with video? You mentioned graphics card so it must be agp or pci so can you try a different card?

I wont tell you to re-do the cpu as you have already done that.

Have you re-set the bios?

As stduc said, can you check the monitor on another computer? Or try a different monitor.

It just might be wise to take the mobo and all out of the case at some point. I agree with your thinking but it wouldnt be the first time that taking the mobo out of the case solved the problem. Sometimes something falls into the case and causes a short, you just never know.
Have you taken all non-necessities out of their pci slots?
Or disconnected any usb or other goodies you might have?

Finally, double check all connections, take them apart and re-connect them.




Good advice + great people = tek-tips
 
Rapid, multiple beeps usually indicates a video card problem. Do you have another video card you can try? PCI or AGP doesn't matter, we are looking for the problem - not effeciency.
 
It's not the monitor. I've tried another graphics card - no luck. I've reset the BIOS and disconnected all goodies. Only remains to remove MoBo.
 
Do you know how to re-set the power supply?
If you havent done that then i think you might want to try that.
Failing that, I think at this point you would be wise to remove the mobo and start from scatch with this unit.
Take everything all apart and put it all together a bit at a time, reading the manual, which, if you dont have, you can download from the mobo mfgr website. If problem with id of the mobo, give us the info from the mobo and we will help you with that and whatever else it takes to get this puppy up and running again.

Also, can you give us a lowdown of the make and model of mobo, power supply, vid card, etc, whatever might help.

Once you have it all totally apart, try the mobo connected to the power supply with no cpu, see what you get out of it at that point.



Good advice + great people = tek-tips
 
Something else to look for: bugs! You'd be surprised on what can be between the motherboard and case.
 
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