8400 Will not boot

Question

I am working on a friends 8400 that no longer boots. There are no lights lit of the 4 on back, the front power switch is solid amber. The standby power light on the mobo is lit green and the video card also has a light lit on it.   So far I have removed and reseated all cards and ram. I have removed 1 of the 2 dimm's and tried each that way with no improvement. Cleared the cmos via jumper.   I am out of ideas. Gut says power suppy but I don't have a back up for these with sata drives to test. Anything I missed in the way of testing?

shesagordie · Answer

hdstn

A solid amber could mean a failed motherboard. You could try unplugging the power cord, then press and hold the power button in for at least 10 seconds, then reconnect the cord and turn on. But, in most cases replacing the motherboard is the answer.

If the power supply is fine. You try removing all the PCI cards, the video card and memory, disconnect the IDE/SATA and FD cables, then check that the front panel cable is connected to motherboard, with nothing else connected to the case, except the power cable and then power the system on.

If you do not get any beep codes or no diagnostic LEDs on the back panel, then it would appear that the motherboard has died.

If the computer, is not under warranty, you can buy a new Dell OEM D-8400 motherboard for $29.00 from here,

http://www.centrix-intl.com/

To test the 24-pin power supplies, I've a PSU tester is best,

http://www.cwc-group.com/pojuatxposut.html

Bev

Spot_the_Redtar · Answer

Hdstn,

Try this: At the back of your PC, find the voltage toggle switch just below the power cord, it would indicate if it is 115V or 240V, use a ballpen to toggle the switch from 115 to 220 and viceversa for at least five times but make sure to put it back to 115. Try rebooting with the monitor and power cord only, if it gives you an image then try pluging the keyboard and mouse next. If it still does not work, try opening the system and reseat the processor on the motherboard and hopefully that will resolve your issue before you replace it.

Goodluck

Spot_the_Redtarget

hdstn · Answer

Thanks for the ideas. I will give those a try. Also ordering a ps tester, too many times wished I had one.

There were some errors received before this refusal to boot happened. The errors resulted in bsod as I am now being told. I will try and get some more specifics and post them.

Really appreciate the info on the mobo. Providing the ps and processor are ok that's a pretty cheap fix.

Will update as the diagnosis progresses.

shesagordie · Answer

hdstn   Thanks for the heads up.   Bev.

Sergio Torres C. · Answer

Please see the following threads, about the same problem: http://forums.us.dell.com/supportforums/board/message?board.id=dim_other&message.id=283876&query.id=233827#M283876 http://forums.us.dell.com/supportforums/board/message?board.id=dim_other&message.id=283179&query.id=233848#M283179 http://forums.us.dell.com/supportforums/board/message?board.id=dim_other&message.id=282164&query.id=233868#M282164 http://forums.us.dell.com/supportforums/board/message?board.id=dim_other&message.id=280867&query.id=233991#M280867 http://forums.us.dell.com/supportforums/board/message?board.id=dim_other&message.id=280564&query.id=234022#M280564

hdstn · Answer

Sorry it took so long to get on this. Got a mobo, thanks again for the link, and while doing the swap found a burnt connector. It is the 4-pin yellow/black connector that plugs in right under the cpu shroud, reason I never saw it when diagnosing, until you disassemble it's almost invisable.   Curious to what this plug powers. I can't find a schematic on the board. I would like to find out just what blew and maybe figure out why.   Does anyone have a line on a good replacement ps for this unit. Going to just replace it rather then take a chance.

hdstn · Answer

Thanks, I could not find that diagram earlier. I have found that this P2 plug powers the cpu (or so I read anyway) and yes it was burnt. Hope this doesn't violate any rules but this thread at another board is pretty much identical to my scenario: http://forumz.tomshardware.com/ce/Dimension-8400-wont-boot-ftopict51352.html

So right now its either take a gamble on a ps for ~$30 (thanks again for the link) which I have no confidance in solving the issue or looking for a cpu or telling him to scrap the sys and buy new. I really am disappointed in Dell on this one. Seems as if this is/was a very common issue. Furthermore, whats to say after all this it isn't going to happen again as all the replacement parts are Dell. Doesn't really make sense.

shesagordie · Answer

hdstn

Are you refering to the square 4-pin P-2, because there have been several posts about arcing and burnt P-2 connectors on motherboards.

This is the best info, Dell has published on the D-8400 motherboard,

http://support.dell.com/support/edocs/systems/dim8400/SM/techov.htm#wp1052739

You should be able to buy a Dell OEM D-8400, 350w power supply for $25-$28 plus S&H, from Dell Spare Parts, call 1-800-357-3355 option 4, M-F 7 to 7 CDT and have the system's "Service Tag" handy.

http://warrantypartsdirect.dell.com/us/program/T1421000.ASP

You need a PSU model Rev A01 or higher [latest Rev A10].

or from here,

http://www.centrix-intl.com/

Bev.

Please don't send me questions about your system by DCF Messenger.
Post the issue in the appropriate Board, where they will be answered.

shesagordie · Answer

hdstn

That's a tough decision to make. Personally, I would invest in a new $30 power supply.

Bev.

Please don't send me questions about your system by DCF Messenger.
Post the issue in the appropriate Board, where they will be answered.

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8400 Will not boot

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