stillerz

Have you cleaned the dust from the case fan, heatsink cooling fins, front panel air intakes and the inside of the case recently?

Bev.

 

Stillerz,

I'm having the exact same problem with my 8400.  it just started about two weeks ago and has happened 3 times when I put the computer in standby mode.  I have to shut off the computer manually to get it to stop.  What is the high speed emergency cool down tornado mode sound like...I think mine is closer to that.  Have you had any success in trying to find a solution?

I'm hesitant to mess with the CPU and heat sink but I might have to go do that.

Good luck.

Chris

The fan on my 8400 is running loudly also.  It started doing it occasionally and then stop.  Now it is loud all the time.  I cleaned the dust flashed the bios but nothing helps.  I read other forums that indicate it is a problem with the 8400.  One indicated that Dell is aware of the problem and has fixed it out of warranty if you complain enough.  Seems the heatsink is the problem.  Can I use the computer with this problem without worry of ruining the computer.  It seems to work fine just the noise.

SP

SMARIEP

When you clean the dust out of the case, did you clean the cooling fins of the heatsink and the air intakes in the front panel, have you tried removing and reseating the video card?

Check the motherboard for capacitors with bulging tops or are leaking, the tops should be perfectly flat.

You should be fine running the system, but there's a chance the fan will burn out as it's on high speed all the time.

Personally, I would try installing a new heatsink, call Dell Spare Parts HERE for a replacement.

I have a 8400 that had the same problem and replace the Dell heatsink with a Zalman CNPS7700-Cu and have had a silent 8400 for over two years.

Bev.

Well, I went from a problem to a standstill.  I opened up the computer and blew out the dust from the heat sink and began to attempt to remove the heatsink but couldn't get the first clip off.  I decided that it was too late in the evening for me to mess with it, but I took that time to install some new RAM I bought.  I plugged in the power and heard a loud click or pop.  Now I get nothing.  There is a small light on the Motherboard, but I get no diagnostics light in the back and no other sounds.

I followed some advice to take out all RAM, cards, and reseat them.  Still nothing.

Any advice gang?

Chris

Topherbone

Is the power button LED, solid green, blinking green, solid amber, blinking amber, or not lite?

If you are comfortable around computers, you could try the following to test the 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 on and if power supply fan and hard drive run, 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.

Bev.

Bev,

Thanks for the advice...I think I had seen some of your other posts, but was hoping to avoid going past my comfort zone.  I jammed a paper clip into the green wire area and a black wire area and got nothing.  I'm guessing that the PSU is bad...which might explain the strange fan problem earlier?  I have no LED lights on the outside, either on the back panel or on the power button.  I do have a green LED on the motherboard (I think it's labeled Aux_pwr).  Anyhow, out of all of my current options, I think buying a PSU replacement might be the way to go as a first step.  Any suggestions?

 

Thanks,

Chris

Topherbone

Before you can check the other components, you must have a 'know' working power supply, therefore the power supply would be the first part to replace.

The 8400 systems can use most standard generic ATX power supplies, with either a 24-pin or 20+4-pin main motherboard power connector, without the on/off switch and a minimum of two SATA power connectors.   

If a power supply with the switch is installed, you will need to cut a hole in the back panel for it.

A 8400 OEM 350w power supply can be purchased from either HERE, or from Dell Spare Parts HERE.

Bev.

Well, I was about ready to reply and clam success with a new power supply.  I installed a supply from SCEUSA and powered up the 8400 which worked great.  I shut down the computer, loaded in my extra ram, got it set back up as my media computer...and ran it for two days, like a champ.

This morning I tried a restart and now the computer hangs during startup...I haven't had a chance to mess with it, but its at least turning on again...we'll see what's next.

Thanks again for all of the help up to now.

Chris

Topherbone

Happy to hear that replacing the power supply worked and the 8400 is running again.

Bev.