Compaq NC8000 push the start button fan runs for 20 seconds and shuts off, removed all devices changed memory,removed processor and reseated applied heatsink compound.remove batterys, unpluged cmos battery let set for 10 minutes and repluged cmos battery. still no video and still run 20 seconds and shuts off with no video even pluged ext monitor same thing happened. noticed wireless and battery lights come on but no hard drive ever lights up.

Hi:
Here is what I would do...
Turn the PC off and unplug it. Then press the power button to drain any residual power from the motherboard.
1. Remove and reseat the memory module(s). Restart the PC.
2. If removing and reseating the memory module(s) doesn't work, if you have more than one memory module installed, remove all but one, and start the PC.
Test each memory module one at a time, until you find the one that is bad.
If none of that works, check for bulging and leaking capacitors on the motherboard. These may be particularly noticeable around the processor area.

First check the processor fan is working if working remove the memory from the slot clean with a clean cloth and rub the conector with a erasor dont use any metel or any other thing insert the memory and see if the lock is locked on to memory properly still not working change the memory sutable for the memory slot still not working removce the processor heatsink and the processor clean the surface and apply athin layer of heat sink compound and fix back the processor if still not working change the processor if still not working use an addon graphics card and check for display

Hi, Lets try this to isolate the problem.
1. Hold down the power button just to check if the power button switch is not the one defective, if it continues with initialization then switch might be defective,
2. Second isolation was the power supply, since you had changed it already we proceed to next step,
3. remove/reset the cmos battery, the memory and the processor for 20 minutes and other cards in expansion slot.
4.After 20 minutes install the battery, memory and processor and video card. If it has the on board video, use it first before using the video card in expansion slot if any.
5. Power on the PC.
6. If still the same our last resort of problem would be the mother board itself.

Identify the pin point of device by swaping of RAM / Processor / and Board.
Then replace / repair accordingly.

first shut down you computer remove the covers of the cpu then locate the memory and remove them wipe them clean with clean cloth and switch the computer on with out the memory and see if you hear any beeps if you hear beeps insert the memory and switch on the computer if still no beeps then remove the processor fan and clean the surface of the processor fan and the processor apply a thin layer heatsink solvent and clip the processor fan tighty to the socket

Hi Kindly let me know how many times the red light blinks
Condition Code Service Actions Processor thermal protection activated. Power LED blinks red twice, once a second, followed by a two second pause.

1. Make sure the computer air vents are not blocked and that the cooling fan is running.
2. Open the hood, press the power button, and see if the processor fan spins. If the fan is not spinning, make sure the fan cable is plugged into the cable header on the system board, and that the fan is properly installed and seated.
3. If the fan is plugged in and seated properly, but is still not spinning, replace the processor fan.
4. Reseat the processor heatsink and make sure the fan assembly is attached to the heatsink properly.

Processor is not installed. Power LED blinks red three times, once a second, followed by a two second pause.
NOTE: This condition indicates a missing or improperly installed processor, not a defective one.

Make sure there is a processor in the system. Reseat the processor and verify that it is installed properly. Power failure (power supply is overloaded) Power LED blinks red four times, once a second, followed by a two second pause.

1. Check the voltage selector, located on the rear of the power supply, is set to the correct voltage (the correct setting depends on the region).
2. Open the hood and make sure the 4-wire power supply cable is fully connected to the power connector on the system board.
3. Check if a device is causing the problem by removing all attached devices (such as disk drives and expansion cards), then power on the system. If the system enters POST, power off and replace one device at a time, repeating the procedure until the system power failure reoccurs. Replace the device that caused the failure, then replace each of the other devices and confirm that they are functioning properly.
4. If you cannot isolate the failure to a specific device in the previous step, replace the power supply. **
5. Replace the system board.*

Pre-video memory error. Power LED blinks red five times, once a second, followed by a two second pause, and five simultaneous beeps are sounded

1. Reseat the DIMMs in the memory slots on the system board, then power on the system.
2. Replace the DIMMs one at a time to isolate the faulty module.
3. Replace 3rd-party memory with HP memory.
4. Replace the system board.*

Pre-video graphics error. Power LED blinks red six times, once every second, followed by a two second pause, and six simultaneous beeps are sounded. For systems with a graphic card:

1. Reseat the graphics card and then power on the system.
2. Replace the graphics card.
3. Replace the system board.*

For systems with integrated (on-board) graphics, replace the system board. PCA (system board) failure. ROM detected failure prior to video. Power LED blinks red seven times, once a second, followed by a two second pause, and seven simultaneous beeps are sounded. Replace the system board. Invalid ROM based on bad checksum Power LED blinks red eight times, once a second, followed by a two second pause, and eight simultaneous beeps are sounded.

1. Reflash the ROM using a ROMPaq diskette.
2. Replace the system board.*

System does not power on. No beeps or blinks since the system is not functioning. Press and hold the power button for less than four seconds. Perform the following steps depending on whether the hard drive LED turns green.

If the hard drive LED turns green, then:

1. Make sure the voltage selector (which is located on the back of the power supply) is set to the correct voltage for your region.
2. Remove the expansion cards one at a time until the 3.3V auxiliary light on the system board turns on. If removing a card turns the light on, replace the card and then see if the system works.
3. Replace the system board.*

If the hard drive LED does not turn green, then:

1. Make sure the computer is plugged into a functioning AC power outlet.
2. Open the hood and make sure the power button is securely fastened in the power harness and that the harness is connected properly to the power connector on the system board. In other words, make sure that the power button is making contact with the power circuit.
3. Make sure the power supply cables are connected properly to the power connectors on the system board.
4. Check to see if the 3.3V auxiliary light on the system board is not turned on, replace the power supply. **
5. Replace the system board.*

Good day sir, hi, You need a thorough check on your PC.
But first try testing the Motherboard, Processor and Memory module.

As this point you need a friend, that knows how to tinker with your PC

Or you may need to do this.

1. memory testing:
Try replacing a new memory ram module on your PC, get the modules out of the memory slot, and let it be tested on another PC. if good,

2. power supply
Test for the power supply box, remove the 20/24 pin power connector from the mainboard and short the green and any black wire, your fan should blow out air.

3. Test for motherboard.
remove all coonections from the motherboard, except the 20/24 pin power connector, and the 12v 4-pin molex power connector, connect the pc speaker or the thumb speaker on the speaker port, connect a keyboard, clear the CMOS, (or remove the battery temporarily), connect the header panel (power switch, reset, power led) place the processor and memory (the tested good one). power on.


You should hear a beep (good) The keyboard will light up the three leds, then a few seconds, the numlock led.

If you hear 1 long and 2 or 3 short beeps, problem with the display section. Reseat any graphics card. test again.

If you hear continous beeps, reseat the memory, if the beeping persist, replace your motherboard.

If you hear nothing? only fan blowing, replace your motherboard.

I can only give you instructions, you need a someone who knows how to service a PC.

Hi!

Please check for the cables coming into the motherboard from the power supply. Also try and check for any loose cables.

If that doesn't help then please get your power supply changed as its faulty.

Please rate this solution.

Thanks
Rylee

Hi,
YOu can change or upgrade the ram by either of the two sites below,
www.memory-express.co.uk/M--Compaq--Business+Notebook--NC8000.html

or

www.datamemorysystems.com/Compaq-memory/Business-Notebook-nc8000

Hope my info solves your problem...
Thanx for using fixya.

If it's not beeping during the first start up then it's not POSTing.  Beep means everything connected to it seems to be functional ie PnP  
Try pulling out your memory and reseating it.   Try pulling out your battery for 5 minutes then plug in ac(without batt) and see if it will boot.  Try pulling your hard drive and reseat.  (access by covers on bottom...dont be scared. Touch something that's grounded just before you remove) If all this and still no full POST(with beep/s) then sounds like a new mobo or processor.
James Mac