Question Oldie but Goldie... With Strange

[trebor58]

Hello, I have a Dell M6400 that was working fine, then stopped (just died). I switched it back on, and it did not boot; instead, the No. 9 bag (Num Lock) led flashed 23 times and then remained on. According to the Dell Precision™ M6400 Service Manuals, it signifies a processor error.

So here is what I have tried so far.
1) Removed and cleaned the CPU, reseated it, applied new thermal paste and retried and got the same error.
2) Purchased a replacement CPU, applied new thermal paste, and retried and got the same error.

Now, thinking this is not the processor, I purchased a replacement motherboard and tried both CPUs, but I still get the same error message.

So please, any suggestions...

 

[trebor58]

Unless I tear down a working M6400, no

 

[COLGeek]

Understood. The idea is to isolate the problem. Since you already swapped a couple CPUs and motherboards, logically you would then look at what was common (as you noted earlier).

Otherwise, it seems you really can't get to the bottom of the issue.

 

[adamgrace]

This is more likely a power or VRM issue rather than a CPU issue. For example, if both CPUs and another motherboard are giving the same error code, I would check the PSU, DC jack, and RAM as an option. As a faulty power path can still cause the CPU error LEDs to light up on this model.