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- non ECC?
December 1, 2005, 4:04 pm
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I wonder if anyone can tell me how I can see if a memory is ECC or not? I
have just bought a memory module, 512 mb PC2100 ddr and don't know if it is
broken or if it is ECC. My mainboard does support non ECC only. When I start
the computer with this memory it sounds like an ambulance´s sirene or
Re: non ECC?
There are two attributes to memory, and three useful combinations.
Unbuffered without ECC (most common for desktop memory use)
Can be used in a motherboard that supports unbuffered memory.
Unbuffered with ECC
Useful if you want reliable computing, using large qty of memory.
Motherboard must support ECC, in order for the extra expense to
be worth it. If the motherboard doesn't support ECC (the
signals are not wired up), the module will still run as if
it is "Unbuffered without ECC".
Enable ECC option in BIOS if present. All modules must be ECC
for the computer to be able to protect the memory properly.
Registered with ECC
Used on server boards.
Use of register allows larger memory arrays to be used.
Incompatible with an "unbuffered only" motherboard.
Will squeal like a bastard, if plugged into the wrong board.
The fourth combination, registered without ECC, is not very
useful, because someone running a server would want the extra
reliability of having ECC error detection on their registered DIMM.
You have probably bought registered memory.
In the following picture, there are three chips below the nine memory
chips. When you see those three chips, that is evidence of a
registered memory. Nine memory chips tells you the memory is
72 bits wide, and the ninth chip does the ECC lane. (There are
plenty of ways to build modules, and that is not the only way
to do it.)
Re: non ECC?
Does your motherboard still work ? If you plug some other memory
in there, is it recognized and does the computer still boot ?
If your MS6585 is still working, then that implies the memory did
no permanent damage. You could try the memory stick you have
purchased, in another computer. This might tell you if this is
just an incompatibility between the BIOS of your MS6585 and what
the BIOS is reading in the SPD chip of the DIMM. (The SPD chip is
a tiny chip on one end of the DIMM. It holds the timing information.)
It could be that the DIMM is just bad, and testing it in more than
one computer might confirm that. If you have any doubts about the
DIMM, send it back to the vendor.
When you eventually get the computer working again, test the
memory with memtest86+ from www.memtest.org . You download the
program, and when you execute the program, it will format a
special test floppy for you. The floppy can be used to boot
the computer and run the test. No errors are acceptable, if
you see them printed on the screen. Run at least two passes, to
see whether the memory has any serious faults. (If the computer
doesn't have a floppy drive, the memtest.org site also offers
a ISO CD image, suitable for burning a bootable CD.)
I cannot think of another reason, right off hand, as to why
the memory is not recognized. Do you have a URL for the web
site where you bought the memory ? Do you have a part number
(as seen on the label of the DIMM) ? Perhaps tracing down
the source of the memory, will show what other potential problems
it could have.