Question about Dell Dimension 8400 PC Desktop
Got me some BIG problems here with my 8400, 40 months old and well out of warranty. For the most part, she has run flawlessly, with the exception of a bad stick of RAM about 6 months ago. I replaced all (4) sticks of DDR2 512mb with (2) new 1gb sticks. All was well until 6 days ago when I got home from work. I hit the power button and got a solid amber power button light and a "rocket ship" for a fan. LoL. I thought the thing was about to fly to the moon. I've never heard a computer fan so loud in my life, it was akin to a vacuum cleaner. I couldn't power off via front button, so I had to pull the AC cord. Upon replacing the cord, unit "took-off" again w/o my pushing the power button. It was a combination of pulling the cord and pushing the button simultaneously before I could get the tower to stay off and be plugged in. When I attempted to start-up again, same rocket ship fan issue. I did get the thing to boot eventually by, again, some funky combination of pulling the AC cord and pushing the power button as well as some "jostling" of the tower. When it did finally start, I kept it running for (6) days while I removed data from it, saving music, pics etc. to an external drive. During the (6) day period it was on, I did re-start on (2) occasions, via Windows, not by turning off and on again. It re-started with no problem. Finally this morning, I turned it off and let it sit while I showered. Upon my return I attempted to turn on and you know it....amber light and rocket ship fan. Once again I was able to get it to boot with the funkiness of pulling, jostling, and punching the button. I have search online for similar issues and have found many with the same problem. It seems that all the others with the same problem have had 87 different ways to fix this. Does anyone have a sure-fire way to remedy this?? I've read about PS, MoBo, CPU, RAM just to name a few. Any help is greatly appriciated!!
Pc turns on and fan is very load and will not boot what can i do
Posted on Dec 12, 2009
I own & operate a computer reapair store. I recently worked on a Dimension 8400 that sounded like a jet taking off. I removed the heatsink, cleaned the heatsink & cpu, applied thermal grease & reattached the heat sink. It booted up quietly...after testing it several times...the turbo fan, jet engine sound returned! I removed the heatsink and along the upper part of the cpu I could see where the heatsink hadn't made contact with the cpu! I added more thermal grease & reattached the heatsink. It started fine on several attempts before the jet engine sound returned. I tried applying uppward pressure on the heatsink so it would close the apparent gap between the cpu & heatsink and when I pressed the power button...it started up quietly! At least I identified the source of the problem...not sure how to fix it yet.
Posted on Nov 19, 2008
I have a small business where I have worked on PCs for the past 14 years. I have had some of my clients that have brought me a few of these Dell 8400 to work on with the same problem. Will not boot and loop the start up, along with sounding like a leaf blower. After much trial and error i.e. Heat sink,cooling fan, power supply and motherboards. The first one I worked with by changing the heat sink, worked for about a week, then started doing the same thing. Replaced the Power supply with no results, same issue. Next was the Motherboard, still same issue. Last I pulled the processor out and found that the processor had over-heated and was damaged. In all I had well over $500.00 dollars invested and countless hours. Still the machine did not work, and still needed more work. Since this time I have had a few more of these machines cross my path. My suggestion is to scrap it and purchase a new PC. This is not one of Dell's better designs, and there is a tech issue from Dell related to this problem with the heatsink and the machine itself in the tech support on the Dell site. It states that they had a bad batch of heatsinks, but only replaced them under warranty.
Salvage what you can and build or have someone build you a clone.
Posted on Aug 07, 2008
I had the same problem with my Dimensions 8400. I redid the thermal paste/grease but the problem continued. I discover that by getting more downward pressure on the heatsink unit fixed it (albeit by using an unorthodox method). I folded some tinfoil (the same surface shape of the top surface of the heatsink to the thickness of a few millimetres) placed on top of heatsink and so when the green cover for the heatsink is pushed back into place it helps to apply more downward pressure on the heatsink eliminating any gaps between heatsink and CPU.
The problem in the first place might be down to the bracket for the heatsink becoming weakened over time.
Did this last week and computer working fine and starting up without the racing fan.
Posted on Aug 18, 2009
In a follow up, my solution was a new mobo. I got a $80 older, 'compatible' board (long story on getting it in the case), but it been working fine since. IMHO and research, the problem comes down to heatsink, mobo, or cpu. My theory is the problem starts with the heatsink, either it goes bad or the conductive gel does (looked like it my case). If you are lucky and catch it early, this is all you have to fix. If not, then the heat damages either the mobo or the cpu, and then its a ****-shoot to figure out which it is. In my case, $80 and 4 hours of my time paid off. Now, I hope I can make it to tax-refund time to get a new primary machine, and this one can be back up. :-)
Posted on Oct 23, 2008
Had the same problem. Replaced battery for CMOS on the motherboard. Computer works fine now.
Posted on Dec 06, 2009
My 8400 is over 5 yrs old now,and i recently had the cpu fan go into leafblower mode,couldnt shut the thing down by holding in the power button so yanked the power lead out.The strange thing is that the pc was idling at the time,and had been on for a couple of days,no programs or games were running,so i doubt its an overheating issue.Also,since this happened i have been playing pretty demanding games (farcry2 & fallout3) with no issues.One thing i did notice while investigating this was that the molex plug to my graphics card was loose,i unplugged it and tried to boot to see what would happen if the card wasnt drawing power,and the fan was much louder than usual but no where near as deafening as leaf blower mode,so i think pjmarkert is onto something with the overvoltage theory,but what could make it occur at a totally random moment,and be ok after a reboot?Hmmm
Posted on Nov 22, 2008
I have a dell optiplex gx240, once i push power, the cpu fan goes crazy, sounds loud like the pc is about to blow up, and nothing shows on the monitor, i took the cpu fan out and put some thermal compound on the heatsink/cpu and tried starting it up again and it still does the same thing, can anyone help me?! lol
Posted on Oct 23, 2008
I had this same problem and simply took the mem cards out then put them back in. After that it worked like a charm. However, once my fan kicks into "high" it won't downshift to any other setting, so it is loud most of the time.
Posted on Aug 29, 2008
Same issues (no boot, loud fan and amber power).
Posted on Jul 17, 2008
Same issues (no boot, loud fan and amber power). Called Dell and they said they will send dispatch.
Posted on Jun 27, 2008
If the fans are rediculously loud, ie much more than normal high speed, there may be a serious overvoltage problem in th ps. If that is the case, you may fry everything in the box eventually, or start a fire. DON'T LEAVE IT PLUGGED IN TO POWER UNATTENDED. Try swapping out the power supply. A peripheral such as a disk drive may be shorting the 5V and 12V together. It is more likely that the 12V is going overvoltage since the fans run on 12V
Posted on Apr 04, 2008
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Posted on Jan 02, 2017
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