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Subject:
From:
Bill Cohane <[log in to unmask]>
Reply To:
PCBUILD - PC Hardware discussion List <[log in to unmask]>
Date:
Sun, 15 Mar 1998 08:27:41 -0500
Content-Type:
text/plain
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At 15:43 14-03-98 PST, David wrote:
>Intermittantly the post memory chk will lock the system. Sometimes on
>cold boot but more often on warm boot.
>
>This is the first time i have tried using edo memory so I'm not sure if
>I am using wrong CMOS setting for EDO. I have Award BIOS. I usually use
>non parity and set dram ECC/Parity to ECC. and Memory Parity/ECC check
>to Auto. Or do I just have bad simms. I hate to spend more money on
>simms to find out.
>
>Any suggestions?


ECC stands for Error Checking and Correcting. Depending on the chipset
and circuitry used on the motherboard, for ECC to be utilized, your
memory must be either Parity RAM or ECC RAM. (Both of these types of
RAM use 9 bits instead of 8 bits per byte. See below.)

Anyway, if you *don't* have either Parity or ECC RAM in your computer,
then setting your BIOS to anything other than "Disabled" for both parity
and ECC willlikely cause big problems.

I assume you are using either 72 pin SIMMs or 168 pin DIMMs. Non-Parity
(8 MB) RAM SIMMs would be labeled something like "2 MB X 32" whereas
Parity SIMMs would be labeled "2 MB X 36". (Note that 32 is a multiple
of 8 and that 36 is a multiple of 9.) If you see the 32, it's non-parity,
non-ECC RAM. If you see the 36, it's either Parity or ECC.

Non-Parity (16 MB) DIMMs would likely be labeled "2 MB X 64" whereas Parity
DIMMs would be labeled "2 MB X 72". (Note again that 72 is a multiple of 9
and so provides the extra 'bit' for parity or ECC checking.) A DIMM is
functionally the same as two SIMMs on one module.

Parity EDO SIMMs would be rare, if they exist at all. ECC EDO SIMMs
are available but would be more expensive than regular EDO SIMMs. You
would not be likely to have them unless you went out of your way to
special order them.

ECC EDO DIMMs are more common, but again, you would not have them unless
you specially asked for them. EDO is now passe with the new PII motherboards.
Everyone wants "SDRAM" with the advent of the TX and LX chipsets.

Before anyone can give you definitive advice, you need to tell what
motherboard (Manufacturer and whether 386, 486, Pentium, PII, etc.),
chipset (e.g., Intel 430FX, VX, TX, HX, 440FX, 440 LX,..., non-Intel...)
and type RAM modules you are using. If you don't know what type
motherboard you have, it can be deduced from the BIOS identification
string listed on screen at boot. Wim's BIOS Page at
<http://ping4.ping.be/bios/numbers.shtml> can tell you what motherboard
goes with what Award BIOS. (Or maybe <http://www.award.com/>.)

<http://www.crucial.com/> is a good place for information about RAM.
(Crucial is Micron's memory division. Micron makes high quality RAM.)
Another great webpage for RAM information is
 <http://www.kingston.com/king/mg0.htm>.

Please note that I don't have much experience actually installing RAM
or using different motherboards. The PC technicians on the list can
help you if you provide them more information.

Regards,
Bill

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