Laptop rebooting continuously....

[shoride]

Hey all have a dilemma that I am sure you can all help me with, so here goes.
Friend brought me an HP pavilion dv6700 laptop. The laptop continuously restarts itself. It does not get to any bios screen at all. All the lights come on for 2 seconds then it shuts down and cycles back on again. It will continue to do this until I pull the battery.
Here is what I have tried so far.
1) Pulled the hard drive and tested, all is OK
2) Reseated Ram
3) Pulled CMOS battery out to reset Bios
4) Pulled main battery out and tried starting with just the power cord.
I am guessing at this point it is the motherboard. I did work on an identical laptop recently that I had to replace the motherboard on, and after some research found that it was a common problem with this model of HP laptop. The computer I worked on was an easy diagnoses, it did nothing at all. 250.00 later for a new motherboard and all was fine.
Anyway I digress, this is something new to me never had a computer act this peculiar before.
Any ideas?

[Train]

What is the name brand on the power supply and its size.

Sounds more like a ps [power supply] going bad to me.

[shoride]

It is an HP original power supply. The battery seems to be fully charged. The computer acts this way with or without charger connected.

[Train]

Remove the battery and see if it will boot with just the AC adapter.

[shoride]

tried that as well with same results...

[Train]

Have you check the air passages for being plugged up?

Can you see the cpu fan? is it working, plugged up, etc?

[shoride]

I can see the fan and it has virtually no dust buildup. When I attempt to turn on the system the fan starts to spin then stops as the laptop then reboots itself.
Strange behavior for certain.

[Midknyte]

There were some HP laptops with bad Nvidia video chipsets. DV6700 is the series number, so you need to find the actual model number. Then you can check if it's covered under a service recall.

[shoride]

This is model number dv6812nr. I checked and it is not part of the service issue.

[shoride]

I disassembled the laptop and reseated the CPU and heatsink/fan and added a little thermal grease for good measure. I then reassembled it all and tried another boot up. Same results as before. From the research I have done online (as well as personal experience from another HP laptop I recently replaced the motherboard on) all seems to be pointing at a bad motherboard. I am planning on ordering the replacement motherboard tomorrow unless someone comes with a magic solution! From what I have read HP did have problems with the dv6000 series motherboard failing, unfortunately this particular model is not included in the service warranty...........isn't that always the way
Thanks all again!

[merle211]

I'm having an identical problem on the same series laptop. How can you be sure it's the motherboard? Is it worth trying a new battery?

[jdc2000]

The dv6000 series laptops should be able to run with the battery removed and the AC adapter connected. If you have tried that and you are still in a reboot loop, then you can most likely eliminate the battery as the cause. There are some laptops that won't run with the battery removed, but the dv6000 series should be able to do that.

[shoride]

Yea I tried without the battery with the same results. All things point to the motherboard. But it also may include or even be limited to the processor. I will probably replace both as a precaution.

[shoride]

Ok a little update on this issue. I ordered and received a replacement motherboard for this laptop. I removed the CPU from the old motherboard and inserted into the new one and then replaced it all back into the laptop and.................nothing. I do not even get any lights now. The only light showing is at the plug in for the power cord. Am I missing something? Is it possible the replacement board is faulty?

[gosho_zl]

I've got the same problem with my hp pavillion dv6123eu since last April. It stopped working after I pressed the Enter button to get into internet. At July last year i decided to try again to start it. It has started to reboot again and i put in the CD-ROM a bootable CD with LINUX and after about 30 min. restarting the laptop started working. After starting Windows I changed the BIOS with a new one. The laptop had worked about two weeks and after that - the same problem, it is rebooting continuously. I removed the HD device and connected it to my PC and it worked. Maybe the problem is coming from the mainboard? What would you say?