Re: NMI ??

Dominik Kubla (dominik.kubla@uni-mainz.de)
Thu, 29 Apr 1999 01:29:22 +0200


On Wed, Apr 28, 1999 at 11:08:05PM +0200, Mathieu Arnold wrote:
> Hi
>
> Yesterday, i added 64Mb of memmory to a box i have (compaq deskpro 575, 2.0.36
> kernel) and it never got to recognise it. I tried to boot linux and it got it
> all. But during the boot, i got this :
>
> Uhhuh. NMI received. Dazed and confused, but trying to continue
> You probably have a hardware problem with your RAM chips or a
> power saving mode enabled.

You didn't write what the total amount of memory is, but since you added 64MB
it might be a problem with the 2nd-lebel cache. But that is unlikely to raise
a NMI.

More likely problems are:

1. ECC or Parity enabled and the SIMM have no parity bits (some are sold
fraudulent as SIMM w/ parity!)
2. The new SIMMs are defective.
3. The SIMMS are drawing too much power, thus resulting in weak bits triggering
parity errors.
4. Not all SIMM sockets on the board are equal.
5. The SIMMS have different timing parameters.

Now here's how you check things out:

1. Remove the OLD SIMMs and put the NEW SIMMs in their place.
If the SIMMs are fine, everything should work. That takes care of problem
#2.
2 If not, check the BIOS that ECC/Parity are disabled. If things work, #1
is settled.
3. If not reconfigure the memory timings most conservative. That should take
care of #5.
4. Now add the OLD SIMMs. If all works, we have settled problem #4 and you are
finished.
5. If not, then you have most likely run into problem #3. In that case get
a technician and have him check the power supply unit for current jitter.
If the PSU is okay, you'll need to monitor current and voltage during bootup.
That is tricky and should only be done by a service technician.

If that doesn't work, you're most likely out of luck. I have two such
mainboards at work. They will be replaced ASAP...

Yours,
Dominik Kubla

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