Do I need a new motherboard on my Mac Pro?

[Vigvetteman]

2007 Mac Pro 8 core
( posted in Mac Pro section but no responces )
Ready to pull my hair out over this....and thanks for any help offered in advance!

Long time Mac lover, user & tinkerer.

I have a Mac Pro 8 core 3.0ghz ( A-1186 )
Inten Xeon 5365 CPU's
The build date Aug 7 2006
The motherboard sticker 630-7951
2.1 vers.
Purchased used,last month, has not run correctly yet.
This was going to replace my G5 2.3 dual.

This Mac looks like is was in front of where the owners would dump out their
vacuum cleaner... so I went inside and cleaned EVERYTHING.
and put new Arctic silver on the CPU's.

The machine boots off the hard drive or a boot disc.
I'll get all the way up and can start using the machine for a limited amount
of time.then black screen , boot chime & restart. and the more " load " ( read game or something processor intensive ) causes it to restart faster.

While running looking at the motherboard diagnostic lights
The GPU light goes away.and the EFI GO blinks off.
The machine shuts down & restarts right back up......

Im stripped down to 2GB of memory ( 2 1GB sticks ) in the bottom..
This cycle takes about 7 minutes when the machine is " cranky ".
And it's random... last night I ran for 2 hrs with NO ISSUES...
this am .. back to the 7 minute thing.
On restart..
Trickle on..
Power on..
Then the EFI GD.. goes on & stays on
Then the GPU light comes on..
( the gray Apple screen and the spinning gray " gear " icon )
Get to blue screen
Get to desktop
GPU light blinks~
EFI blinks~
commence restart...

I have tried the following
Measured power supply 4.96 & 12.05
Reseated EVERY connector
Reset the PRAM
SMC reset
PMU reset
New battery
Brand new Apple video card
Tried 2 KNOW working DIMM holder cards & know memory.
Sacrificed a goat & chicken as a last ditch effort.


But then I called Apple support.. ( which confused me more ).
They state the following...
I have the Ram installed incorrectly..
Each of the matched pair should be 1 single stick in the upper 1 single stick in the lower. ( the machine will not boot in this config ).

NOR will it boot with a pair in the top AND bottom cards..
But either card , one at a time in either slot will boot.

It will not make it through apple hardware test.
And at this point... I think I have a memory controller issue
So I guess my motherboard is gone...
We love Mac's states I need a 661-4307-R for a replacement.

Opinions,thought's or suggestions?

HELP

Thanks


Mike

 

[Vigvetteman]

update.....

So if I hold the power button while plugging power in.. the Mac goes into hurricane mode.. and NOW I am able to run..

I just did a clean install... that was OK.
Just downloading updates.. going smooth.

So it's obvious something thermal( that isn't monitored ) is happening in my MP.

Mike

 

[Vigvetteman]

... and further Mac Pro 8 core info

So I was able to pass hardware test in Hurricane mode.
I installed a fan program to run the fans up to 1500 rpm.
This allowed me to run, update and do everything like I normally would do.
BUT
I still cannot put known good ram into the bottom pair on the DIMM holder.
So I guess my motherboard is KAPUT...

Mike

 

[chrismacguy]

Sounds to me like a thermal issue (dust may have caused this) has caused the motherboards memory controller to fail... Are you following the hieroglyphics on the door in regards to installing RAM?

 

[Vigvetteman]

Yes Chris

I sure am ( unlike the advise I got from the phone peeps @ Apple Tech support ) .. I have tried different risers and memory combo's that WORK...

I can have 2 sticks in the top or bottom.. but not both at the same time
( DIMM sockets 1-2 )

I'm going to try another experiment in a little bit.. like 4 in the top, nothing in the bottom.

I also notice.. the later machines have a MUCH bigger heatsink for the north bridge memory controller chip.

This rig did get the Quiznos treatment... you could just smell it...
Just like an Xbox played a bit to hard with no ventilation.

Mike

 

[chrismacguy]

I sure am ( unlike the advise I got from the phone peeps @ Apple Tech support ) .. I have tried different risers and memory combo's that WORK...

I can have 2 sticks in the top or bottom.. but not both at the same time
( DIMM sockets 1-2 )

I'm going to try another experiment in a little bit.. like 4 in the top, nothing in the bottom.

I also notice.. the later machines have a MUCH bigger heatsink for the north bridge memory controller chip.

This rig did get the Quiznos treatment... you could just smell it...
Just like an Xbox played a bit to hard with no ventilation.

Mike

hmmm - might be worth trying to swap the RAM backplane, if thats not it (as both could have been fried by either inquisitive child, or Quiznos crumbs) then its probably the memory controller on the logic board, so it probably does need a new one - shame, but at least its a Mac Pro, so its worth saving

 

[Vigvetteman]

Oh yeah...

So it does " see " the ram in A 3-4 ( running 60 min test now )
The same RAM went into B1-2 ( No boot )

I have 2 " spare " dimm risers... all behave the same..

I can put ram into the top or bottom and things boot... running together.
No tango...

( Whoops I just heard it reboot )

CRIPES!

Mike

 

[Vigvetteman]

Ok Tech tools made it run to hot

Running memtest now....
seems to be happy ( er ) .

Now it DID just fail apple hardware test ( since the fans were " normal" ).
But once the OS ( 10.5.8 ) is running it lets fan controller work...

Which it was twistin up a fair bit ... but cooled down like 4 seconds later.

Mike