Dell Dimension 8400 wont boot up

I have a dell dimension 8400. when i turn it on the cpu cooling fan comes on and sounds like it wants to take off. Nothing else happens. The monitor stays black.
Further to this problem.
I checked the power supply with a multimeter and it seems to be good. All the recommended voltages were where they should have been.
The four lights on the back A B C D are all off.
The 3 lights on the keyboard flash on and off when i turn it on.
Can someone out there please help.
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  1. Quote:
    I have a dell dimension 8400. when i turn it on the cpu cooling fan comes on and sounds like it wants to take off. Nothing else happens. The monitor stays black.
    Further to this problem.
    I checked the power supply with a multimeter and it seems to be good. All the recommended voltages were where they should have been.
    The four lights on the back A B C D are all off.
    The 3 lights on the keyboard flash on and off when i turn it on.
    Can someone out there please help.

    You might try mounting a different drive in C:, then booting from your install CD. If you get the same, likely some hardware problem.
  2. I couldnt do that. I cannot even get to the CMOS menu as there is nothing on the monitor. As I said in the beginning all that happens is that the CPU cooling fan works nothing else
  3. Out of warranty? Time for the repair shop.
  4. Quote:
    I have a dell dimension 8400. when i turn it on the cpu cooling fan comes on and sounds like it wants to take off. Nothing else happens. The monitor stays black.
    Further to this problem.
    I checked the power supply with a multimeter and it seems to be good. All the recommended voltages were where they should have been.
    The four lights on the back A B C D are all off.
    The 3 lights on the keyboard flash on and off when i turn it on.
    Can someone out there please help.

    Let me guess - the light on the power button also stays a steady yellow/amber? If so, your system is showing the EXACT same symptoms as my 8400 just started showing on Monday. Usually, if it was the PSU, the power light would be blinking yellow/amber instead of being steady on. After doing some reading at the Dell forums, I'm pretty sure it's the mobo that's died, so since mine is out of warranty, I went ahead and ordered an OEM replacement from a 3rd party and it should arrive tomorrow.

    If I have time before I have to go to work, I'll install it, see if it takes care of the problem, and post here with the results.
  5. Thanks for answering my problem. Will watch for your answer.
  6. Well, unfortunately, replacing the mobo didn't seem to work. I was cautious to the point that after putting in the new mobo, the only 2 things I put on it before powering up were the CPU and the CPU fan. The result was the same - the power LED was steady yellow/amber, the CPU fan spooled up to hyperspeed, no HD activity or video output, and the 4 status LED's on the back of the case did not light up at all. So, I didn't bother connecting anything else.

    I also purchased a new power supply (470W Silencer 470) and tried that with the same results.

    I think the only other culprit could be the CPU and, at this point, I'm undecided if I'm going to bother replacing that. I might just buy a barebones system and move my peripherals over instead. :?
  7. Thats bad news. I was hoping for your sake and mine that the new mobo would have been the fix. I might follow your lead and go via the barebones idea.
  8. Try putting in a video card from another computer and disabling onboard video, if that is what you have.
  9. Dont you have to do that in Cmos. Cannot get to Cmos as nothing comes on the screen.
  10. I've had a similar issue to yours. I noticed one morning that my machine's cd lights, power etc were all blinking.

    I unplugged the machine and plugged it back in, when I did, the fan was superspeed, and smoke came out the back, and there was a burnt smell. After reading Dell's forums, several other people had the same issue and noticed their MB p2 connector ( next to the processor is burnt, and also the power supply connector that plugs in.

    I've replaced MB and PSU, but now the diagnostics show a bad cpu.

    I believe dell has a serious issue with this connector, but their tech support will not escalate this. I am concerned about the safety of this MB/PSU. My computer didn't catch fire, but I don't know if that is because I was there to unplug it.

    Please check your p2 connector to see if your connector is also burnt. I'm trying to get someone at dell to look into this more closely, so that this doesn't seriously harm someone or their property.

    thanks, Patrick
  11. Just for additional info, I did not have any indications of overheating or smoke or any other problems. I had just started playing a game and everything froze on the screen and since nothing else was working, I powered off. I turned it back on and it did boot up and I was able to log onto XP, but just as it got to the desktop, it froze again. I turned it off and back on, but this time the screen stayed dark, the CPU fan went into hyperspeed, and power button stayed steady yellow/amber and that was it - no HD activity and the 4 status LED's on the back of the case never came on.

    The very first thing I did was remove the the Radeon X800 XL card I'd been using for over a year and put back in the X300 that came with the system, but that obviously didn't work. I then started removing/disconnecting stuff one-by-one, trying to power up in between each time, and obviously that didn't work either. That's when I started checking the forums and thought that replacing the mobo would work.

    In any case, I've since inspected the original mobo and there aren't any outward physical signs of anything being burnt out. The capacitors aren't bulging and there aren't any dark spots on the back side of the board.

    I may have a line on getting a functioning P4 540 (3.2 GHz) CPU from someone to at least see if that works in the new mobo, but I'm not sure yet. Of course, if I'm able to get it, I'll post the results.
  12. Just an update. It turns out my problem was the CPU. I was able to borrow a P4 530 (3.0 GHz) and placed it in with the "new" mobo I had purchased and the computer fired up fine. I took a chance (since it was a borrowed CPU) and put the CPU in the original mobo and it also worked there.

    So, I went ahead and bought a P4 541 (3.2 GHz with EM64T technology) and I've put that it in the original mobo and everything is working fine. I've also went ahead and replaced the original 350W PSU with the Silencer 470W that I had, though that required some modification to the rear of the tower to accomodate the AC outlet which is below the opening for the OEM PSU.

    Hope you get your problem fixed.

    (Edited to change MHz to GHz - sort of a big difference...oops)
  13. Glad to hear that you got it working. I havent done anything yet but will try a CPU as soon as I can,
  14. I bought a USED Pentium 4 3.2 Ghz 541 800mhz SL8J2 LGA 775 CPU and it didnt change the situation.
    I then bought a Gigabyte MOBO GA-81865GME-775-RH ( to upgrade my own PC from a socket 478 to a 775) and that way i could test the CPU i had bought and it worked for a couple of hours. I then put the original Dell CPU into the new MOBO and have been running it for the last 12 hours straight. Nothing wrong with the original Dell CPU.
    Looks like it must be the Dell MOBO.
  15. If your able to do all that with hardware, why are you buying Dells?

    Save the headache and just build your own.
  16. I did'nt buy a dell, it's my eldest daughters, I would'nt have one if they gave it to me, just trying to help her out of a mess.I told her to get rid of it, I guess she will when she has some spare cash.
    regards Henry
  17. Well the problem has been solved. I found a MOBO on ebay for
    AU$33.08 and fixed it. Thanks for all who tried to help.
  18. very strange..I just setup my dell 8400 again and had this exact same problem.. I stopped using this dell about a week ago when the parts came for my new computer. This computer was working perfectly fine, no freezes, lockups or random reboots, for about 2 years..then today, dead
  20. lol, so, 3 people with similar problem.. tommygrime's problem was the powersupply, Handyost's problem was the motherboard, and kirby34's probelm was the cpu.. think we've just determined the heh. Thanks for posting your guys findings here though, might end up getting mine up and running eventually
  21. I have a Dell 8400, had it for about 2 years. I am experiencing the same problem as you had. My computer did overheat it was running at like 160 degrees F. When I look at the lights on the back A is amber, B is green, C is amber, D is green. Occasionally I can get it to start up and it runs fine I have the tower open and settings for performance instead of quality. Except this time when I powered it down I haven't been able to get it to restart.
  22. Well mine jsut died, took about a week doign funny things, blue screen, then the video woudl go blank, turned it off and restart it woudl come back on but then die a hour later. then it just did nto come on other than the lights, switched out the power supply and nothing, switched out with a OEm dell 8400 same motherboard and nothing, did th ememory thing and guess it is the CPU. Funny thing is the dell power supply would just swin up and whien at high pitch. what a waist, 4 months short of 2 years and a dead computer.
  23. This exact same problem happened to me, and I've looked around and there is no definate cause for this as far as i can tell.

    The weird thing is that my computer will start up every now and again and act perfectly normal (all be it very rarely), but most of the time it goes crazy on me.

    There is one solution to this that involves going into BIOS... which may or may not be possible for you.

    I have not tried it personally, but I will as soon as I get it to boot up, and post back here to let you know how it goes.

    EDIT: After about 6 attempts, i got the computer to boot without fan frenzy, went into BIOS, changed the settings, it booted up seemingly fine. But as soon as i loaded my profile, it crashed, only to go into fan frenzy when i tried booting again.

    So i think it is safe to assume it is definitely a hardware fault causing it, and i'll see if i can get dell to send over some replacment parts (what ever part actually needs replacing)
  24. Had the problem today with a refurb I bought. Same problem as mentioned earlier. Symptoms are sudden hangs with the inability to restart/shutoff PC by holding power button, can only shutdown by removing power cable afterwhich the computer may or may no boot up. The 2x2 connector on the motherboard was also singed on two pins as well as the power lead connector. It seems the PC will only do this after being powered up for a few hours or when it attempts to enter a different power state. Seems to be the power supply causing the problem. I can see how over time with these power surges that it could damage the CPU and the motherboard as well as other components.
  25. I had dell come and replace motherboard and CPU, and all is working fine again.

    I didnt see any burnt cables or whatever, but that could well be whats causing the problem. I'll just have to wait and see if it happens again while using my current PSU.
  26. I havent looked at this forum since i repaired my daughters Dell. After replacing the motherboard we had and still have another issue. The PC restarts on shutdown. I have read a few forums to see if others had the same problem and it looks like they have. I have tried all the advice mentioned and still have the restarts on shutdown. My advice to anyone wanting a new PC. DONT BUY A DELL
  27. This problem seems really weird. Maybe it's just luck but my 8400 has had no problems in it's two plus years of service. My question is, have your tried reinstalling windows? A fresh install can cure many woes. (worked wonders for my 4700. dropped processes down from 70 8O to 32).
  28. HI
    No I havent tried to reinstall win xp pro but i will i visit her in a week or so. Will let you know how I go. Thanks for your posting.
  29. I "inheirited" a Dell 8400 from my brother, when they upgraded. There were two known problems from the get-go..first NO memory. I put in 512 mb of memory. Second there was a connector from the face plate to the moBo damaged so I replaced that. Now the machine is intact - power on, power supply fan starts lights blink, no go..doesnt power up, doesnt blink amber, nothing. I just ordered a PS hoping that will be the last thing I need to replace. In anyones "professional" opinion does it sound like a PS problem? Powers up for less than 2 seconds. Back lights blink then go black.
  30. Hi I had a similar problem I also found that changing the power source and the CPU helped me solve it, but I had some advice from a tech support site.

    Here is the page for Dell Dimension 8400 Support

    I hope this will help

  31. I managed to reinstall windows xp sp2 but it didnt make any difference. the pc still reastarts on shutdown. One of these days I will do a complete format and reinstall. Maybe that will solve the problem. Anymore advice will be helpful.
    The only advice for HudVal69 is that I think you need a new MOBO.
  32. My 8400 has been running quite well for about 2 years it seems like everybody else's and is still on warranty. For about 2 months or so, the fan is running loudly and is not dirty. I go to turn mycomputer on when i get home and the light is solid amber w/ no led's in the back on. Turns out, when i call dell and they walk me through troubleshooting it, theres a power supply to the motherboard (the one closest to the fan w/ 4 prongs) the cable is burnt up. They guy at dell tells me hes sending me a whole new tower and that i can just plug my current hard drive into it. Just hope that can help someone else out there and am also wondering if anything will be different on my new cpu even with the same hard drive as before. ie. settings/information/software.. thanks
  33. I am pretty sure that all will be the same.
    It was with my daughters when i replaced her MOBO.
    You are lucky that you had the extended warranty.
  34. My 8400, 2yr - 3mo old, suddenly didn't power on at all. No external lights front or back, no sound, no fan, nothing changed when I hit power on. Opening the case there was a small green light on motherboard; all looked OK. I first followed procedures on Dell site and then called. After a bit more than the site tests, the tech support concluded that it was the motherboard and suggested I buy another from them. This is expensive (out of warranty) and I wasn't fully convinced that was the answer. (I've since seen that 3rd parties offer the 'mobo' more cheaply). So I brought the 8400 to a local Geek Squad. They looked at it for several minutes and then pulled and reseated the cpu. They'd seen that loose before on a 775 board. This worked, all rebooted and came up OK. When I got home the 8400 was in the nothing at all status again. I brought it back and this time they also pulled and reseated the CPI boards. Again all OK. I was extremely careful driving home and all was good at home. A few days later (after cleaning lady (a factor or not??)) it was (is) absolutely dead again. I suppose I should just go back to the Geek Squad, but thought I'd try to see if I could learn more on-line. However my pattern seems just slightly different than others' experience above in this forum and likely the devil is in the details. Maybe the 'mobo' is the problem but maybe not - I and wondered if anyone else has more experience/knowledge about this OK/totally dead/OK pattern. Thanks much for ideas.
  35. Add me to the list. Exactly the same problem - fried CPU. I had my 8400 about 3 years and 2 months before it finally started having all the symptoms you guys have had. I mainly use it for video editing and rendering. I did install a small room fan in the cabnet where the computer lives (err, lived). Could be the external cool extended its life? Who knows. Probably a bad design in reqard to heat management. My solution - I just bought another Dell. Lets hope the Core2 duo E6500 is a better processor!
  36. OUCH! I just had the exact same problem... after 3yrs 8 months.
    No Status lights coming on and amber power light. The fan whirs and the LED on the motherboard lights up. However I noticed that some air inlet vents were blocked up with fluff - this could have caused the CPU to overheat. Longshot though... will see if I can get a cheap CPU to try, otherwise i will bin the PC. ;/
  37. I have similar problem. i power the computer on and the fan revs real high but monitor stays black. usually i have to hold the power button in to shut it off turn it back on a few times this way before the computer turns on normally. it resumes normal usage and works perfect.. you can turn it off and back on like normal.. but if you turn it off once it starts for more than 30 minsutes to an hour or so.. once the comp cools down the problems boting it up starts again. It seems to me liek a cpu or MoBo problem but took it into geeksquad to have it diagnosed and they ran software/hardware analysis on it and found nothing. so now we are stuck as i don;t want to spend money on a solution that won;t work seeing as it could be more than one components that is causing the problem( cpu/mobo/powersupply/ect.). i am hoping i can find someone who knows WTH they are talkign about.
  38. I have the same problem, the fan sounds like an aircraft building up to take off.
    Get the PC in a good light (fluorescent) and look at the capacitors, they should be straight sided cylinders. If ANY of them look "fat" then it is a new motherboard you need. The capacitors swell up inside (like a really old zinc/carbon battery) and stop performing as they should - new motherboard.

    I'm trying to troll through the web looking for a replacement.
    Spec from Dimension Manual & Dell forums;
    Intel 925X Express or Intel 925XE Express, Socket LGA775, System Clock 800 or 1066 MHz data rate (depending on your processor), MemoryT ype 400- and 533-MHz DDR2 unbuffered SDRAM
    The most important item is the LGA775 Socket Type, any other and your CPU will not fit.
    You might buy a new motherboard & CPU (some places do bundles).
    Whatever you do check that the replacement will fit the fan hood.
  39. I couldn't find any motherboard which would physically fit in the case and line up the Graphics PCI slot.

    So I decided to buy a full size ATX board and a new ATX case. Hopefully the Dell power supply will fit in the case I get (or can be "persuaded") but the heatsink fitting will be a problem, I may need to get a new heatsink/fan assembly as well.
    I bought a Foxconn 945P7AD-8KS2H ATX Motherboard, via Amazon for £46.
    I'll let you know what happens.
  40. Been watching this thread for months. My 8400 had the same symptoms--no boot, CPU fan sounding like a turbojet, just months out of my 3 year warranty. Started happening intermittently then just gave out. I started with the cheapest part and worked my way up (all purchased on ebay)--new heatsink tower, PSU, CPU, then motherboard. Of course it was the motherboard.

    But someone in this thread mentioned something that I should have keyed in on--"bulging" capacitors. I was thinking of something like bulging out the sides or scorch marks. No. My old mobo had capacitors with rounded tops--kind of bullet shaped instead of flat-ended cylinders. If I'd paid closer attention I would have replaced the mobo first.

    Ironically, a couple weeks later the PSU went out (simply no power except flashing yellow light on power button), but fortunately I had a new spare already!

    Good luck everyone.
  41. Just to add that I found this forum today because I am having the same problem with my 8400. It's encouraging to know I'm not the only one, but discouraging to see how hard it may be to fix!

    Oh, and by the way, the warranty period expired one month ago.
  42. These problems all stem from one thing: heat. The early P4 prescotts used in these Dells were simply too hot, and consumed too much power, especially in conjunction with a decent graphics card, for the stock PSU to handle in the hot environment. Dell's stock cooling solution was inadequate for these Prescott CPUs. Dell chose quiet operation over effective cooling, and the price to pay for such a decision is rapid component failure, namely the PSU, CPU, and mobo. Dell's earlier Dimension series, the 4500/4550 line and 8300, did not suffer these problems, as they were equipped with cooler running Northwood P4s.

    Also, sucks that you all own Dimension 8xxx series towers. Their proprietary mobos make it impossible to put in aftermarket mATX mobo, or to put the factory Dell mobo into a better ventilated aftermarket case. You could try an get a mobo tray from a Dimension 4500/4550 series, as it supports aftermarket mATX mobos, but even then the unique all-in-one front panel connector is a serious hurdle to overcome. In short, the Dell 8xxx series, and especially the 8400, are poorly designed computers.
  43. I, of course, have the same issue. My screen froze and I had to unplug it from the wall to shut it down. When I tried to power it up again all I got was the steady amber light. I went through dell support and pretty much unplugged everything and plugged it back in. It seemd that unplugging the PSU from the mother board is what did the trick. It worked fine for a day and the same thing happened. I unplugged the PSU again and it worked for about 20 minutes and the same thing happened. I'm going to replace the PSU tonight. I will let you know how it goes. I am not even close to computer hardware savy, so this has been an adventure :-)
  44. Add me to the list, what is so galling is that when I bought my Dimension 8400 in 2005 it was promoted as a top spec machine (and top price) but so many of them can't make their third birthday. It's a disgrace.

    I had same symptoms - no boot up, just a mad fan on turning the power on, and for me either no lights or just the "B" diagnostic amber light (this configuration has no reference in the diagnostic light tables!).

    It wasn't my PSU, but from this forum I know it is either the MOBO or the processor. On removing the processor I found one of the connectors underneath either damaged or melted.

    I salvaged the memory, graphics card, and SATA disks and PSU and chucked the MOBO. I'll build a new one from (not Dell) parts. The MOBO had to go as it is damaged, but there's no point re-using the CPU is it runs too hot which caused the problem in the first place.

    Oh one more thing, I've kept the heat sink and CPU for prosperity. The sink is a big ugly beast and compared to the wafer thin CPU looks ridiculous, it'll be in a museum one day and people will go "no, never!!"
  45. I have a 4700 with a very similar affliction - front panel amber light comes on at power up, power supply fan is going, but not much else. Several months ago I called Dell support and the diagnosis was a failed mobo. When I replaced it, things did work, but during the swap I noticed that two of the connections on the P2 connector were charred. I decided to "clean" (scrape using the end of a large paperclip) the inside of the two charred P2 connectors and also the corresponding pins on the mobo. This exposed enough conductive surface to get more months of service from the original mobo (I just had to clean them again). I've also been turning the PC off every night (it used to run 24x7) to slow the deterioration rate.

    However, as noted in earlier messages, the real problem appears to be too much current draw through pins 3 and 4 of P2 (12VDC -

    The CPU is a 3.2Ghz Intel P4. Is there a different/newer CPU that will fit the socket/heat sink configuration in the 4700 and draw less power?

    I could buy another power supply (just to get a new P2 - what a waste!) and install the refurbished mobo, but that would just postpone the inevitable P2 deterioration since I'd still be using the same CPU.
  46. Ok, it's been a month since anyone has posted but ill give this a shot.
    Im in the same situation, I have a dell dim 8400 that wont start. It gave me the loud fan, the frozen screen just like most of you other folks. Im not unfamiliar in terms of doing repairs myself but this had me stumped until I found this forum (for that im grateful). Anyway, ive read everything written here carefully and there seems to be some confusing info maybe someone can clarify for me. Is it, or is it not possible to relace the mb and cpu on this thing with after market parts? One highly rated member eluded to the fact that they would not fit the original case, while others say they have replaced their parts. If it is possible can someone please tell me exactly what model mb and cpu out there that will do the trick... I dont have the $$$ to buy a new pc and unfortunately i depend on the 8400. I have an online data entry job and its been a pain in the *@#...

    Here are some tech specs on it for you much needed help:

    P4 541 (3.2 GHz with EM64T technology)

    Thank you for any help!
  47. You cannot replace the MB in the 8400 with aftermarket. Simply won't screw in. You can replace the CPU, but the factory motherboard restricts you to Pentium 4 5xx or 6x0 cpu, no Pentium 4 6x1 CPUs will work, and no Pentium D/Core 2 Duo will work either.

    The cheapest way to repair your 8400 is to do the following: buy a cheap ATX case, a cheap LGA 775 heatsink, and a cheap LGA 775 motherboard. Swap over the CPU, ram, PCI cards, hard drive, CD drives (even power supply if you wish) into the new case. Use your old Dell XP CD to install Windows XP, then call Microsoft to activate by phone, give them the product key on the side of the Dell case, and tell them you had to replace the motherboard due to failure. Total cost for the Case, motherboard and heatsink should be a bit less than $100, which is about the going rate for another 8400 motherboard, but if you buy another oem board you're not fixing the source of the problem and just setting yourself up for another failure down the road.

    My recommendations:
    motherboard: $50

    Case: $34

    Heatsink/fan: $14

    Total price: $97.95

    That should work well, as long as you don't have more than 2 PCI cards or more than 2 sticks of ram. There's a chance that it's the CPU to blame and not the motherboard, but that's very, very rare. 9 times out of 10, it's the board that went bad. Good luck
  48. :bounce:

    Thanks a ton Joe! This info REALLY helps me out...

    You da man
  49. joefriday said:
    The cheapest way to repair your 8400 is to do the following: buy a cheap ATX case, a cheap LGA 775 heatsink, and a cheap LGA 775 motherboard. Swap over the CPU, ram, PCI cards, hard drive, CD drives (even power supply if you wish) into the new case.

    This thread has been a well of information. I too have a Dell Dimension 8400. But I have experienced a slightly different problem. My Dell doesn't do anything when I try to power up. No fan, no lights nothing. I have checked the power strip and cord, all are fine. Inside the case when its plugged in I see the small green LED light on the mobo, other than that its a boat anchor.

    Over the last 6 months or so I would have trouble using the reset button when the computer froze. I would have to unplug it to get it to cycle. About 4 months ago, while at work, my Girlfriend told me that it made a lot of noise like a jet engine taking off, much like what others have described above. She had to unplug it to get it to stop and since then its happen a few times. The last time i had to shut it down before this, it didnt want to come back on for a little bit. started to power up then went dead, waited a little bit and hit the button again and it booted up fine.

    Am I correct in thinking its either the power supply (probably not) or the Motherboard (most likely)? I am really considering Joefriday's solution about just getting a new case, fan and mobo to solve the design flaws of the 8400 case. Or should I just get the dell mobo to replace it? Money is an issue :) but this replacement solution looks like it comes with a lot of benefits and want to know how hard is it to do?

    Thanks for all replies.
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