M17x R3 - insane beeping, but boots & passes ALL tests with no errors

I'm trying to revive a M17x R3.

Upon power up it will will beep sometimes 2, sometimes 3, sometimes non-stop for several minutes before successfully booting up into Windows 7. Once in Windows - no problems (at least yet), no more beeping.

The system passes all diagnostic tests with no issues found
* AlienAutopsy
* Dell Online PC Diagnostics
* Alienware Systems Diagnostics (PSA)
* Alienware Enhanced Systems Diagnostics (ePSA) - will beep going into the tests but stops beep part way through (seemingly random)

This system was given up for dead by the original owner. The hard disk had died and his 'tech' then went and created more problems.
Don't know when the beeping issue started.
* I replaced the bad hard drive installed Windows 7 x64 and added all the Alienware drivers, etc.
* had to reseat the CPU (apparently wasn't locked down tight enough)
* fixed the keyboard intermittent problems (cursor keys were flakey) by reseating the cables.
* removed the graphic's card - AMD 6870M (no change in beeping)
reinstalled it, reseated the GPU cooler applied new thermal paste.
* reflashed the Bios - no change.
* it has 2 2gb RAM chips - testing with either or both shows no errors.
* the external video port works fine
* audio works fine (internal speakers)

At this point except for the beeping on power up everything appears to be working just fine.
But without knowing why it's beeping like this I'm leary of upgrading the RAM or spending the time to install all my software, etc.

Any ideas?

 

You've done a lot there. Beeping can be a problem when it's intermittent (that's happened to me) but definitely exasperating when like yourself you've done a lot to try to ensure everything is ship shape but still the beeps carry on.

For what it's worth here's the beep code table:

Alienware Beep Codes Table - Alienware Forum - Alienware Club - Dell Community

 

Thanks for the code table.

Most often its 3 beeps on startup, but it varies - mainly between 3, 4 & continuous beeps and sometimes combinations of these.

Per the beep table
3 Possible Motherboard Chipset
4 RAM failure (other)

and per a post in official-alienware-m17x-r3-r4-owners-lounge-thread-273-print.html
continuous beeping is a RAM error.

The RAM passes all the tests and it appears to be the correct type. So at the moment I'm leaning toward it being a motherboard problem.

How good are the diagnostic tests?
They indicate that everything including the cabling is good - but before I reseated the keyboard connectors the number pad, right cursor & scroll lock keys weren't functioning properly and everything tested as fine. I'm wondering if previous owner/tech got into the bowels of the machine and failed to reconnect something properly.

 

It's pretty accurate.

 

Tried replacing RAM and still same issues (wasn't likely, but grasping as straws here).
Trying one last thing before I have to start either throwing serious money at this system or dump it - a complete teardown and reassembly.
As I mentioned earlier in thread someone has previously been into the guts of this machine (CPU wasn't adequately tightened down, keyboard connector not properly seated, etc.) so maybe other components weren't properly seated either. While it would be really nice it this did the trick, don't really expect it to fix things.
Quite possibly what I'm dealing with is some ESD damage. If I have to replace the motherboard the teardown will serve as a practice run.

Motherboard has PAR00 LA-6601P Rev:1.0(A00) stamped on it.
So if I I have to replace the motherboard, based on that and
http://forum.notebookreview.com/ali...m17xr3-part-number-list-reference-thread.html
it looks like I'll be looking for 5VYM9-PAR00-LA-6601P

Are there things I should watch out for (avoid a certain revision or use a different model of motherboard instead)?