Need help on my M6400...

The M6400 was having random blue screens such as "DPC Watchdog Violation" and one other which I can't remember now.

Everything will usually work alright after a reboot. However, one day it failed repeatedly after 3 reboots and after that was no longer able to start up.

If I press the power button, the system will power up only to cut power out abruptly. I started removing the SSD and HDDs. The motherboard then started giving a CPU error blinking LED. I reseated the CPU as per the work manual and at the same time redid the thermal paste.

First power up after that indicated a memory error. So I re-seated the ram and I was back to square one. If I press the power button, the system will power up but cut power off abruptly.

I swapped out the M7820 for a FX2700M. The M6400 is still cutting power off abruptly upon power up. Swapped the M7820 back and left it as it is.

What could be the issue? Faulty CPU? Faulty motherboard? I don't have a spare CPU or motherboard to test it out though...

 

Watchdog usually points towards a broken CPU or power delivery to the CPU. Depending on how hot you let your notebook run it's likely or unlikely the CPU.

 

Looks like I need to get a cheap CPU first to see what's the issue. The QX9300 in it now didn't miss a heartbeat all these while. Could it be due to a faulty CPU fan? You know when the system first boots up both the CPU and GPU fans will kick in. For some reason, the CPU fan didn't move.

The power cut off, to me, is similar to when the CPU overheats and the thermal diode kicks in and cuts power off and shutting the CPU down.

Will get a cheap CPU off FleaBay to give it a try. I'm beginning to suspect the motherboard or the CPU fan or even the right side I/O board with the Ethernet port (as the M6400 was having all sorts of Ethernet port error messages even though it is not connected to anything).

 

I'm getting parts off taobao instead, since I can read and write in Chinese and it is way way cheaper there for the parts!