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2 Bronze

Dimesion 8400 won't boot

My Dimesion 8400's fan is so loud that it is about as noisy as a *** cleaner. It blows papers off my desk. The computer doesn't boot up, though. I have opened the case and cleaned everything, vacuumed out all the dust, taken out and reinstalled all the parts I can, replaced the battery, and still no luck. Any help would be greatly appreciated.

Replies (18)
9 Rhodium

My Dimesion 8400's fan is so loud that it is about as noisy as a *** cleaner. It blows papers off my desk. The computer doesn't boot up, though. I have opened the case and cleaned everything, vacuumed out all the dust, taken out and reinstalled all the parts I can, replaced the battery, and still no luck. Any help would be greatly appreciated.

Damascus2

Is the power switch LED, solid green, blinking green, solid amber, blinking amber?

Check the sequence of the diagnostic lights on the back panel of the case, see Here:

 ftp.dell.com/.../dimension-8400_Owner%27s%20Manual_en-us.pdf

 Are there any 'Beeps', or error messages?

While the case is open, you check the motherboard for any capacitors with bulging tops or are leaking, the tops should be perfectly flat.

Bev.

 


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8 Krypton

Airplane mode indicates bad capacitors on the motherboard and or inside the power supply.




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2 Bronze

No beeps. Capacitors all look good. None of the four diagnostic lights are on. Power switch light is solid and appears to be green, although it might be amber. I am color blind and it's a small light.

9 Rhodium

No beeps. Capacitors all look good. None of the four diagnostic lights are on. Power switch light is solid and appears to be green, although it might be amber. I am color blind and it's a small light.

Damascus2
As there are no 'Beeps' and Diagnostic lights, it could be either a motherboard, or a power supply issue.
If the power light is a solid green, this usually indicates a working power supply, see page 42 of the manual. As you are colour blind, maybe you could ask a friend to help with this.
First check that all the power and data cables are properly connected, including the cables to the front panel, and if you are comfortable working around computers, you could try the following:

Note: The only 100% method of testing a PSU, is to install a known working power supply.

Unplug the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 24-pin power connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and power the system on, if power supply, case fans and the hard drive run, then the PSU may be good.

Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.

Power supply checks out and the system still does not work, again remove the power cord, hold the power button in for several seconds to discharge the residue power, reconnect the 24-pin connector to the motherboard.

Remove all the PCI cards, the video card [if applicable], memory, all peripherals, disconnect the data and power cables to all the drives, check that the front panel cable is connected to motherboard, with nothing else connected to the system, reconnect the power cable and power the system on.

If there is no difference in the diagnostic lights, 'Beep' codes and/or the LED indication of the power button, then it would appear that the motherboard has died and/or maybe the processor.

Note: The good news is, processors rarely fail, as the only method I know of checking a processor, is to install it a compatible working PC, or use a known working processor.

Bev.

 


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2 Bronze

I'm not sure what you meant by jump the wire, but I did disconnect everything except the power supply and the diagnostic lights still don't come on and the fan still blasts. I guess it's time for a new computer. Thank you very much for your help and I'm off to the store.

8 Krypton

Optiplex GX620 or better Mini Tower units are good crossover replacement systems.

https://www.walmart.com/reviews/product/22985035

 


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9 Rhodium

I'm not sure what you meant by jump the wire, but I did disconnect everything except the power supply and the diagnostic lights still don't come on and the fan still blasts. I guess it's time for a new computer. Thank you very much for your help and I'm off to the store.

Damascus2

Good luck at the computer store, have fun shopping.

You can read this document about 'jumping the wire' to test a power supply:

http://aphnetworks.com/tutorials/psu_paperclip_trick

Bev.

 


If my answer was helpful, please click: Kudos
Forum Member since 2001
I am not employed by Dell

3 Argentum

Perhaps the original poster has already bought a new computer by now, but the issue is probably the one described in the following post:

htt p://binglongx. com/2010/12/12/dell-dimension-8400-boot-problem/ (take out the spaces and copy paste to browser)

Certainly I was affected by this issue with my 8400, and you can see from the comments on that article, many others were also affected.

What happens with some 8400s after a long time is that "Prescott CPU produces so much heat, over the years it comes to the point that a slight push from the distorted green fan shroud, combined with an aged heatsink locking mechnism under heat (that’s why some people argue using a screw-based instead of lock-based heatsink), creates (intermittent) loose connection between CPU and heatsink and/or between CPU and motherboard" and so the PC thinks there is no CPU installed.

I got around this issue for about a year by just physically pressing down on the heatsink / shroud when I turned on my 8400. This made the PC 'realise' there was actually a CPU there. For a more elegant solution, the person who wrote the info in the link above, suggests an arrangement with elastic bands.

2 Bronze

Thanks for the interesting post. I have indeed bought a new computer and am very satisfied with 10 years of service from the Dimension. It's just time.

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