Gosh this thread was useful. Here I am posting my results, because I see this thread is still active and I suspect there are 8400 owners out there who will be able to use whatever info I post.
My machine was four years old, a 3.4 gig processor and 2 sticks of 1 gig ram on a Rev 00A system board bearing the part number with the "U" and the 7s and 0s. Original Dell-installed video was an nvidia 6800 GTO on which I re-enabled the fourth bank of processors, but which I did not overclock. Three years ago I replaced the 6800 GTO with an 8800 Ultra and installed a good aftermarket 650 watt power supply.
Three-plus weeks ago it started giving me odd crashes every other day or so, going to double black screens and a hard lock, no noise, nothing, requiring a 30-second push button reset.
It did this only when playing heavy use 3D games or when in the OpenGL screensaver. After it happened twice I set the system on its side and ran with the case open. After the first crash with case-open both the power supply and video card were quite hot.
I installed RivaTuner to monitor GPU temp, since the 190 series nvidia driver sets don't seem to have any option to do that. I found that the GPU was running at 77 deg C at IDLE! Not good. I set the GPU fan to run at 100% all the time, which dropped idle running temp to 60-61 deg C and full bore HD Fallout 3 temps when lots of atmospherics were up to 72-73 deg C. I also checked power supply output and found no significant drops in any of the output channels.
I figured a Windows Update -- which I had JUST completed -- had interferred with GPU fan operation. The problem went away for five days.
Then of course it came back, more frequent than ever.
On the weekend of the 5th the lockups' frequency increased to once every hour or two and happened irrespective of video usage or GPU core temp. The lockups happened at GPU idle. Reboots became problematical. With the case open I noted that some boots "failed" only because the video card failed to re-init. I could see this because the GPU fan didn't start. On a hunch, I waited a while, hit ctrl-alt-delete, entered the WinXP Pro password, and got the Windows sign-in song. Waiting a bit more, hitting alt-F4 and "return" got me a sign off tune. So... Windows was booting and the system was THINKING the video card was there, but the video card never started successfully.
I pulled the 8800 Ultra and rebooted, which gave me a long delay and then 2 beeps -- NOT a "no video song but instead ..... Memory error!
I was able to repeat this consistently.
I didn't have any video cards around to test. The 6800 GTO is in my wife's new machine and all the older PCI cards went to charity last year.... so I put the 8800 back in, let the system sit for a while unplugged, and then rebooted. It came back fine and ran for a few hours.
Last Sunday the system went 100% failure after a crash and REFUSED to boot no matter how long I waited. I pulled the system board battery, waited an hour, and got nothing at all with the video card and 2 beeps without.
Careful examination showed me that several of the bigger canned caps on the system board around the power entry points and memory were bulging a little. The memory is premium lifetime warranty stuff... and I suspect strongly -- but am not sure -- that the board is bad....
Yes, at this point I could have repaired the system for less by going with a new cpu and board combo in a new case, but (1) I wanted to recover the SATA/AHCI drives' data without any hitches, and (2) because of the proprietary software I run for graphics, software development, and CAD, I'm really restricted to a real Intel processor. (Trust me on this please. I know AMDs are just as good or faster for less bucks these days.) The easiest way to address (1) is to reassemble the same system with new parts, and it would be difficult given (2) to surpass the performance of the 8400 for a lower price point sticking to Intel CPUs unless apps are highly multithreaded.
The Dell 8400 system board failure is SO widespread you can actually go onto ebay and get "Dell 8400 System Board Repair Kits" full of electrolytic caps ... but I figure that's problematical. I really don't want to be soldering on this for an hour or two and then still have any problems. The only way to be sure, of course, is to dust off and nuke it from orbit.
Thus, I got onto ebay and ordered a New Dell 8400 system board from a guy with 100% feedback in Round Rock. It was much pricier than the "tested/guaranteed" units from Hong Kong, but it was new and 80 miles away. I ordered a used/tested 775 LGA 3.6 gig/2M L2/800 fsb Prescott P4 from a guy with 8000+ 100% feedback. The chip arrived in 2 days and the system board in 4 -- total expenditure about $150.
Last Saturday night I assembled the new CPU to the new system board, cleaned the heat sink in acetone and then with compressed air, and mated it to the new processor with some premium Antec silver content heat sink compound that cost five times what the regular compound did but which has an order of magnitude better thermal conductivity. I figured given the discussions here about the Prescott's heat, it couldn't hurt, and the difference was only four bucks at the local computer parts mart.
I installed the old memory, hooked up the drives, and used the old 8800 Ultra. I did replace the power supply with a new Corsair 750 I had previously ordered because it was on sale and I expected to build a new "ultimate" system sometime soon.
I hooked up the cables, flipped the switches, pushed the button, and almost immediately got two beeps.
I pulled the video card.
Two beeps.
Quite late I headed out to the local super Walmart, but of course they have only network bits now. It's been a few years since I looked for computer parts in the middle of the night, OK?
Sunday morning I went to BestBuy and found to my surprise that they had a reasonable price on an open box/warranty ATI Radeon 4850 1 gig GDDR3 -- a hundred bucks ( I would have preferred nvidia because I've dabbled in CUDA development, but if you follow the tech news over the past year you know that nvidia doesn't really have anything new below the top end stuff, and it would be VERY tough to match the performance of that 8800 Ultra....). While I was there I picked up four 1 gig sticks of PC2-6400 DDR2 SDRAM because their price was only a couple bucks a stick more than mail order. And I've been without the machine for a week and really can't wait another week. And I did already mention nuking it from orbit.
So I go home and install the ATI card. At this point, it's new system board, new power supply, new video, new CPU, old memory and drives.
Flip the switches and push the button... and I get a CPU fan trying to push the box into a full military power VTOL departure.
I never heard a CPU fan run that hard in my life. But I did find it discussed in this thread. Symptom of a bad video card, if I remember correctly.
New system board, new CPU, old memory, no video.
Two beeps.
That's ALMOST interesting.... OK.....
Old system board, old CPU, old memory, new video.
There go the Marines taking off again in their V22. Not a bad video card, methinks.
Old system board, old CPU, new memory, old video.
Turbines to speed, Batman!
I'm not going to play musical processors and switch CPUs and boards out. Once they're in the socket I don't want to pull them out unnecessarily. Besides, if the old board blew it might have taken the old CPU with it, as far as things look now.
So... whatever happened blew the system board OR CPU plus the video AND memory. Maybe one was iffy and then something else went. But all at the same time? Odd. But there it is.
Yes, I know how to build computers so why did I buy a Dell? At times it's more cost-effective to get a particular level of performance out of parts, and sometimes you get a deal on a box that someone else puts together. At the time I bought it the Dell 8400 was highly reviewed and it beat do-it-yourself by $200 to $400. At least in the short run it did.
Yes, I could have built most of a new, far more powerful system for about the same total cash, especially given that I had the power supply lying around. In fact, I recently DID build a killer system for just a little more than all the new parts plus the power supply cost ... my wife's new system for school: Asus M4A79T 790FX, Phenom II X4 945 Deneb, 4 gig DDR3, dual Caviar 640gig SATA in RAID 1, OCZ 700GXSSLI .... all in a nifty XCLIO case with greenish purple lit LIZA plastic fans a foot across. But in that case I wasn't worried about keeping data around. We knew we were upgrading so we backed it all up and threw away most of the old machine.
SO... if you absolutely must recover your 8400 you can do it, but if you can risk not salvaging the data on the drives run by the proprietary system board's SATA controller, you can indeed build a new and better system from the good scraps.
And I will never buy a Dell again.
- EP, San Antonio, TX
I know this problem was posted years ago but I would still want to try to solve it. THe problem could very well be in the RAM or RAM slot. Take out the RAM, use a pencil eraser to rub on the metal contacts. Blow off excess eraser bits and reinsert RAM. This works 90% of the time on all my computers. I do this when there is power but the monitor does not display.
SOLUTION
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