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August 24th, 2009 19:00

Dell Dim 8400 will not boot !

 I have an older dell 8400 thats my work horse. When I power up I get a high whinning noise from the case fan and does not power up. I have checked my power and it test good. Any ideas as to what may cause this to happen and how to fix it ? I have also checked and replaced the case fan and replaced the thermal gel . Is it possible that the heatsink is bad ? My 8400 uses the case fan with the hood to dispense the heat through the large heat sink.   What had happened is that I did a 6 month routine of blowing off the dust bunnies and rabbits , took off all the cables replaced the sata and ide ,needless to say there was a lot of dust in between the cases and hard drive/optical drives and when I powered it up it sounded like a jet engine (the case fan will spin at a very high rpm ) and will not boot up nor do I get any of the 4 indicator lights on the back panel to light up either. does not even get to the bios. Does anyone know if there is a way to check or tell if the motherboard is fried ? I do not see any of the capacitors bulging  or discolored.  I also have a solid amber light on where the power button is,Normally the power button is a solid green. There is no smell whats so ever ,there is no burning smell nor are any of the wires burnt. Every thing looks normal.  I have since tested the 6 pin PCI-E connector,the P4 connector,The EPS connector,the 5 pin SATA connector and the Floppy connector. This test was done using the new Ultra 7 in 1 power supply output tester. I believe it might be the MotherBoard after all. Does anyone still make the MotherBoard for the Dell 8400 ? Are there still new OEM boards available ?

 

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46K Posts

August 24th, 2009 21:00

discboy321

If you are comfortable working around computers, you could try the following to check out the power supply.

Note: The only 100% method of testing, is to install a know 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, if power supply's fan and the hard drive runs, then the PSU should 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 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 you do not get any beep codes and there is no change in the diagnostic lights on the back panel, then it would appear that the motherboard has died.

A replacement Dell OEM Dimension 8400 motherboard can be purchased from HERE

Bev.

10 Posts

August 24th, 2009 22:00

 I forgot I all ready did those steps as outlined through the dell tech support. Thanks for the web site. Do you know if this is a new oem or a used board ? Thx for your help Bev.

2.8K Posts

August 24th, 2009 22:00

discoboy321,
The best that can be determined from the item description is that it's an Intel manufactured OEM board made specifically for the Dimension 8400. Since there's no mention of it being refurbished I'm guessing it's new.

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46K Posts

August 25th, 2009 11:00

 I forgot I all ready did those steps as outlined through the dell tech support. Thanks for the web site. Do you know if this is a new oem or a used board ? Thx for your help Bev.

discboy321

Given the age of the 8400, I would expect it, to be a 'refurbished' [aka used] motherboard that's been checked for functionality, to find out for sure, try contacting the vendor. 

Bev.

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