Dell Dimension 5100 failling to start

Posted on 2010-01-13
Medium Priority
Last Modified: 2012-05-08
I have a Dell Dimension 5100 that i am trying to repair. The system is failling to show any lights on the front i have one green light on the system board. i have tried reseating the bios battery the memory the hard drive and the main power cable to the system board but i still cannot get the system booted.
Question by:Techdivision
LVL 19

Expert Comment

ID: 26302001
have your tried to click the button next to the power cord outlet OFF and leaving it OFF for few minutes. Plug everything back in and see if it works.

if it still isn't firing up then could be something wrong with PSU. We'll start with the basic and cheapest part first.

do those tests and see how it goes.

Author Comment

ID: 26302116
There is no manual power switch next to the psu power input. The system has been flakey for a while now.
LVL 19

Accepted Solution

Kash earned 2000 total points
ID: 26302187
i suspect it to be a PSU. they are fairly cheap if you haven't got one to test. the most common issue would be PSU not able to supply good enough power to the logic board for it to fire up.

if you know what you are doing then replace it and hopefully it'll all be sorted. if you don't know what you are doing then I'd advise taking it to someone who knows about electricals.
LVL 93

Expert Comment

ID: 26302255
Here my troubleshooting procedure :
Precautions :
-During connecting or disconnecting devices, be sure to have the AC removed
-Temporarily ground yourself, or use a wrist strap for ESD prevention

-With a new motherboard : verify if all mounting standoffs correspond with the holes in the mobo !!
   Or test the motherboard outside the case, on a wooden  (non conductive) surface
-Clean the system from dust, then  test with the minimum setup - disconnect also all peripherals and network cables :
-What to connect :  only  motherboard + CPU + 1 ram stick, video card, power supply
-Verify that the 4-, 6- or 8-pin CPU Aux power plug is connected
-Verify that the VIDEO card has a power connecter - if yes, connect the power to it !
Now power on  your PC : on boot, do you have a display?
-if NO it is one of the connected: RAM, Power supply , video card or monitor, so if possible swap ram, Power supply, video card or monitor - leaving only motherboard and cpu
-if YES, connect devices till the problem shows
*** note : if the fans are running, this shows there is 12 V present from the Power Supply; this does not mean the PS is ok, you still need 3.3 V and +5 V as well; and other signals.
Additional tests and things to try :
-boot without ram, it should beep; (also, without video card)
-try bios default settings, (if possible) or clear the bios by removing AC and bios battery
-renew the CPU heatpaste, and verify that the heatsink is mounted flat on the CPU, allowing for a good thermal contact
-you can also check the motherboard for bad capacitors as shown here :   http://en.wikipedia.org/wiki/Capacitor_plague
-you can test parts on another  PC

The term POST refers to the Power On Self Test  procedure - here a link  with a short explanation  http://www.pchell.com/hardware/beepcodes.shtml

Expert Comment

by:Brad Sims, CCNA
ID: 26302387
Are you hearing any beep codes?  

By "lights on the front" are you referring to the power lights or the four diagnostic lights on most Dell Dimension CPUs?  If so you may find some help here:


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