8400 tower case Broken

Dell Dimension 8400 PC"s use either Broadcom Extreme Ethernet controllers OR, on SOME models of the 8400 that do NOT have ON-board Ethernet connections, SMC Networks Ethernet Drivers. I've seen MANY a Dell Dimension.

Thanks for the information, pretty detailed, I recommend you get all the specs of the Dell dimension 8400 motherboard and buy a compatible one, of course check the CPU first at a friend's home and if the CPU is fine, go ahead and buy and install a new one.

Should work fine. Only issue you may run into is getting the cable settings (master / slave) set up so everything shows up. Most likely if you're replacing an existing one you can get away with just setting the new drive to cable select or what the previous drive was set to though.

Please leave feedback if this was helpful.

Bad Power Supply, sscorbett.

Usually you have enough power to light LED lights, (Like the harddrive activity LED light for add-in cards, that you see on the motherboard), and spin fans, but Not enough power to turn the Processor on.

Dell Support >Dimension 8400 > Service Manual

http://support.dell.com/support/edocs/systems/dim8400/SM/index.htm

Technical Overview > System Board Components

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

harddrive activity light for add-in cards (SCSI LED)

The Dimension 8400 comes with an ATX style of Power Supply, that has a maximum rated Wattage of 250 Watts.
1) ALL of the LED lights combined use less than 1 Watt of power.
2) EACH fan uses 2 to 3 Watts
3) A typical Processor can use 51 to 125 Watts.

Your Power Supply just has enough power to light that LED light.
Weak voltage power rail.
Replace the Power Supply.

[ There are three power rails inside that SMPS.
Switched-Mode Power Supply.

1) The 3.3 Volt power rail
2) The 5 Volt power rail
3) The 12 Volt power rail ]

The ATX form factor for a Power Supply refers to the size, and shape of the case, for one.
Approximately 6 inches Wide, 5.5 inches Long, and 3-1/2 inches Tall.
The ATX power supply case in the Dimension 8400 however, is shorter in length.
It is 4 inches Long. (Depth)

Not an advertisement for the website, nor manufacturer.
Reference for the case size, and power cables needed,

http://www.cputopia.com/hp-400w-dell-dimension-8400.html

Scroll down to see the connectors of the various power cables needed.

You may have a Power Supply with these dimensions, and needed power cables, in an unused computer.
Perhaps someone has upgraded to a better computer, and has an unused computer that you can temporarily borrow the Power Supply for a test unit.

Make sure it has at least 250 Watts (Maximum rated wattage), plus,

1) 20-pin ATX main power cable. (Or a 20 + 4-pin ATX main power cable)

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain20

[ 20 + 4-pin ATX main power cable,

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain20plus4 ]

2) 4-pin ATX +12 Volt power cable

http://www.playtool.com/pages/psuconnectors/connectors.html#atx12v4

Plus the various power cables needed for the Harddrive, optical drive/s, and computer case fan/s, if it/they do not connect to the motherboard.

This Dell Support, and the Service Manual for the Dimension 8400,

http://support.dell.com/support/edocs/systems/dim8400/SM/index.htm

In the Service Manual main menu, left-click on - Opening the Computer Cover

1) Computer off, and unplugged from power. (Always unplug the power cable from the surge protector. Then if the power cable needs to be removed from the computer, do so)

2) Remove all cables to the computer

3) Lay the computer on it's Right side.
(As you face the computer, your right side is the computers Right)

4) There is a Release button on the Top of the computer case, and a Release Button on the Bottom of the computer case.
These are located at the Rear of the computer.

The preferred method of opening the computer case, is to press one release button in at a time, and slightly lift up on the side of the computer case, where that release button is located near.

Then go to the other side of the computer case, press this release button in, and lift up on the computer case.

The computer case opens like a clamshell. The computer case is hinged at the front.

Example:
Computer laying on it's right side. Press the Top release button in, and lift up on the computer cover located near the Top.

Now press the release button on the Bottom. Lift the computer case up.

The computer case opens from the back, towards the front, like opening a car hood.

Here is a picture:

Below is a link to the beep and light codes for a Dimension 8400. Check your codes and reply back if you need further assistance.

http://support.dell.com/support/edocs/systems/dim8400/SM/adtshoot.htm

call dell first tell them the problem,they should help you,or use chat i use that sometimes.

IT MEANS that the processor is not getting cooled enough, try turning on the comptuer with the side panel open, dont reseat the cooling tower, however also check for the four lights on the back of the tower and post the same,,

There are several different solutions for this as posted at this Forum.

http://www.tomshardware.com/forum/51352-2-dell-dimension-8400-wont-boot

1) A lot of people have just removed the Jumper for the CMOS and turned the Power back on and back off and replaced the jumper and/or removed the battery.

2) Several people have reseated the Memory and after booting back up it worked.

3) A few had to replace the Mother Board and CPU but in this instance they had to also replace the Case because the Dell case wasn't really fit for the heat of from the CPU.

4) I had the exact same problem and luckily replacing the Power Supply fixed this for me. I had to cut out the back of the Dell case for the toggle on/off switch but when I tested the old Power Supply it was only getting 5amps and this was causing the Amber/Orange/Yellow light to constantly flash.

I hope this helps!