Failing hardware, what diagnostics tools are good?

[David Whyte]

Hi list,

I know this isn't an Ubuntu specific problem, but it is my Ubuntu
server that is down and I couldn't think where else to turn.

My box died on Saturday.  It just stopped and when I reboot, I can't
get passed the initial grub menu.  When I run in recovery mode, I get
to the point where it says 'Brought up 2 CPUs' and then nothing
happens from there on.  A Feisty live CD allows me to select 'Boot or
install Ubuntu' (or whatever that option is) and it starts, but
quickly halts too.  I have now removed all other hardware (i.e. PCI
cards) from the machine.

I have run memtest on the two sticks of memory I had in the box and
despite testing each module individually and in different slots, it
shows errors.  I got a spare memory module I had in the wardrobe,
which used to work OK (before I put it in the wardrobe) and that is
also showing errors.  I can't confirm any module is perfect as I don't
have a spare box, but surely I can't have three modules that were good
all of a sudden go bad.  I assumed it was some memory controller or
similar that is failing on the motherboard (Asus P5PE-VM, working fine
for 6 months).

I have ordered a new motherboard, but I am now wondering whether it
could be the CPU.  It is a Pentium D, socket 775 and I have only just
found out that memtest will also test the L1 and L2 cache on the chip.
 Perhaps that is where the failing tests are occurring?

Is there any other type of diagnostics tools that I can use to test
the hardware, specifically the motherboard and CPU.  Wouldn't memtest
load into the memory to run and therefore if it is running, the
motherboard is OK???

Please help, it has been a hard week so far without my computer :(

Cheers,
Whytey