Question about Dell OPTIPLEX 960 MT Desktop Computer (Intel Core 2 Duo E8400 250GB2GB) (BO5SC306)

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My optiplex 960 turns on and the 3 and 4 light stay on and it beeps 4 times and then 2 times but it does not come to the logon screen

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SOURCE: Dell Optiplex GX620 computer beeps when powered on. The beep sequence is 1-3-2. What does it mean and how do I fix it?

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SOURCE: my optiplex 960 does not turn on

Dell Support > Optiplex 960 > Manuals & Documentation tab > Service Manual (6460KB),

A) "Light Pattern,
Number 3 - Blinking Amber -
A possible motherboard failure has occurred"

This you must have known........however going on.........

"Number 1 and 3 blinking amber -
A possible motherboard, Power Supply, or peripheral failure has occurred"

The first thing to check with desktop computer failure, is the Power Supply.

If we are to agree that using the motherboard diagnostic LED's, and specifically the No.3 LED was blinking Amber; then we can agree it was motherboard failure in the first place.

However, me? I'm a skeptical computer geek.

I ALWAYS, test the Power Supply's 3 main voltage power rails FIRST, then I may go on to assume diagnoses has led to the motherboard, peripherals, etc.

From there, it's check the Radial Aluminum Electrolytic Capacitors on the motherboard, for visual capacitor failure.

The motherboard chipset going out, is a Rarity.
IF, it does fail; it's usually the Northbridge chip of the motherboard chipset; because it get's the hottest.

(That's why it has an aluminum finned Heatsink on it. Sometimes Southbridge chips do too)

Southbridge chip is next in line.

You don't know how many desktop computers, I have fixed over the years; that the problem was the Power Supply, and not the motherboard, as assumed by the owner.

Also it's all over the internet.

LED's light up, and fans spin; and people assume the Power Supply is OK.
This = No.

1) If ALL of the LED's were lit up at once, they would use less than 1 Watt of power.

2) EACH fan uses 2 to 3 Watts of power.

3) A typical Processor (CPU) uses 51 to 130 Watts of power.
Just depends on what Processor it is.

Therefore a Power Supply with a weak voltage power rail, will have PLENTY of power to operate those simpy little Light Emitting Diodes, and maybe spin fans; but will NOT have enough power to turn the Processor on.

Either test the 3 main voltage power rails, with a multimeter set to DC Voltage, (3.3 Volts, 5 Volts, and 12 Volts),
Use a KNOWN to be good, Compatible power supply; for a temporary test unit.

Power Supply deemed to be good? Go on with the diagnoses.

Visually inspect the capacitors on the motherboard,

What? Are you cra-zy Joe? Did you not read I replaced the motherboard?


That motherboard you have, IF a direct replacement; is an NOS.
New/Old Stock.
Been sitting on a shelf for years.

Electrolytic Capacitors break down over time. It's the 'nature of the beast'.
They have Electrolytic Paste inside, which is a chemical.
It's known to break down over time.

Computer engineers know this, and use capacitors that are rated at TWICE what is needed. 200 percent.
So..........when the capacitor breaks down to 50 percent good, it is still 100 percent good for the application.

New purchase, or not IMHO it could be a bad motherboard.

Another point of interest; Electrolytic Capacitors do NOT always show outside visual signs of failure.
The Electrolytic Paste inside can just dry up, instead of developing a gas, (Hydrogen Gas), and not break the seals of the capacitor.

However, I would make sure the power is good, then disconnect all internal peripherals.

Peripherals are also the Harddrive, as well as the optical drive (CD/DVD drive), and Card Reader or Floppy drive.

(Outside peripherals; Keyboard, Mouse, Monitor, Printer, etc.
Leave Keyboard, Mouse, and Monitor of course; but disconnect any other outside peripheral)

That means disconnect the data cable from Harddrive to motherboard, and power cable to Harddrive.
Also same for optical drive/s.

Disconnect, the two cables from the USB header on the motherboard, for the Card Reader. (media)

Floppy Disk Drive data cable, and power cable, IF used.

LEAVE the front computer case fan connected, as it's cooling for the Processor. Ram Memory is installed also.

(NO graphics card if you have installed one. Connect monitor cable back to the motherboard. {Back of computer > I/O area)

So essentially we are talking just Processor, processor fan, and Ram Memory.

Turn the computer on.
Try to pull the BIOS Setup screen, up.

If no, you have a bad motherboard.

Now remember, this is AFTER the Power Supply has been deemed good.

BIOS Setup screen comes up?
Then reconnect the harddrive.
Good to go?

Then reconnect the optical drive. If drives, connect one at a time.
Then connect the second optical drive.

Good to go?
Then reconnect the card reader.

Had a post from someone on here not long ago; that we went through diagnosing; until he found out the Card Reader was the problem.

If memory serves it was one of the cables, coming from the card reader.

I'm guessing he ran a continuity test on the cable, with a multimeter set to OHM's, to check whether it was indeed the cable; or the USB header on the motherboard it plugged into.

He never stated.

Arranging all that prattle I stated above.......I mean Summation:

1) Test Power Supply voltage power rails, or use KNOWN to be good, Compatible power supply

2) Visually inspect Capacitors on motherboard.

3) Processor, processor fan, Ram Memory, ONLY; see if you can get BIOS Setup screen to come up.

For additional questions please post in a Comment.


Posted on Mar 23, 2013

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2 Answers

How do i reboot a dell optiplex 960 to factory settings if i cannot login?

How to enter BIOS?
1. Turn on or restart your computer.
2. Press "F2" to enter "System Settings" (BIOS) when the DELL icon appears.
Restore the BIOS to default settings.
Press "Caps Lock", "Num Lock" and "Scroll Lock" buttons to light up the corresponding lights on the keyboard. Then, press the following three combination keys:
Alt+E - Clear (Release) the interrupted resources and reallocate resources at next startup. After pressing the combination key, you will hear a sharp beep tone.
Alt+F - Restore BIOS to the default settings. After pressing the combination key, you will hear a sharp beep tone.
Alt+B - Restart the system.
Password clearing method 1: When the password input box appears, type in the password and press "Ctrl" and "Enter" simultaneously.
Password clearing method 2: Remove the PSWD jumper on the MB and start up the system. Set the password to empty in BIOS, shut down the system and reconnect the PSWD jumper.
Hope this method will help you otherwise check Dell Optiplex 960 Manual- for expert's suggestions.

Dec 24, 2016 | Dell Computers & Internet

1 Answer

2 3 4 orange blinking lights/ automatic start up and forced shutdown/ optiplex 960

Log in to: and send this info to Dell. As I recall lights 2,3,4 are either memory or HDD failure.

Run Diagnostic Run Diagnostic Diagnostics can be run on supported Dell devices with a full version of Windows.

Already have an error code from running ePSA diagnostics?

Dell devices come with preboot diagnostics to capture error codes. If you have already run a preboot system assessment (ePSA), enter the error and validation codes with your Service Tag below and complete the steps to resolve your issue. Enhanced Preboot System Assessment Error Code (without 2000-prefix) * Validation Code * Service Tag * Part Serial # (optional) ; ;

Mar 28, 2015 | Computers & Internet

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DMA page register read/write failure

According to Dell you will need to run their diagnostic utility to find out what is really causing this error code

read the part about how to start dell diagnostic

Feb 26, 2015 | Dell OPTIPLEX 960 MT Desktop Computer...

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USUALLY when a computer beeps like this, it indicates a problem with the memory. I'd check that first.

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1 Answer

I have dell 960 switch it on but light turns to orange

Could be several things.

1. could be the power supply
2. inspect the motherboard for bad caps.

If the above is OK. Try removing and reseating the CPU, Memory and CMOS battery.

Apr 15, 2014 | Dell OPTIPLEX 960 MT Desktop Computer...

1 Answer

My Optiplex 960 flashes amber 3 light when powering on.

Hey, have you ever thought that you ANSWERED YOUR OWN question? If you press the power supply TEST button, then it powers up fully? It's NOT the button.......So...what else could it BE then Mitch?

Nov 25, 2013 | Dell OPTIPLEX 960 MT Desktop Computer...

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Dell optiplex GX620 doesnt start

1-3-1 through 2-4-4
Memory not being properly identified or used

Feb 12, 2013 | Dell OptiPlex GX620 PC Desktop

1 Answer

OPTIPLEX 960 error codes 3 and 4 at startup. Solid amber light.

"optiplex 960 error codes 3 & 4 at startup"

Found out by myself the google suggestion to look up the Dell Diagnostics page:
Lights 3 & 4 means "Memory modules are detected, but a memory failure has occurred." Bingo! I didn't actually replace memory sticks, but pulled them out and put back in one by one. Only three out of four sticks were accepted. Works.

Jun 05, 2012 | Computers & Internet

2 Answers

I have dell optiplex gx 150 beeps 6 times and a and b led is amber and c and d led is green

the 6 beep codes will be in a specific timing i.e. two beeps, a space 2 more beeps, and another space and 2 more beeps.

Looks like it may be a memory problem according to the lights.

ad54556.gif Possible memory failure

Reseat all DIMMs and restart the system to retest.

Here is the link to the beep codes and diagnostic lights for your dell optiplex gx 150 HERE

The Beep codes are in Table 2 and the diagnostic lights are in Table 3.

Apr 14, 2010 | Dell Computers & Internet

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