# On the need to use error-correcting memory



## Mumbodog (Oct 3, 2007)

http://lambda-diode.com/opinion/ecc-memory



> Conclusion and summary
> 
> A system on Earth, at sea level, with 4 GB of RAM has a 96% percent chance of having a bit error in three days without ECC RAM. With ECC RAM, that goes down to 1.67e-10 or about one chance in six billions.


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## JohnWill (Oct 19, 2002)

I was always a fan of ECC memory, but then they seemed to dispense with the ECC capability for most systems.


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## Mumbodog (Oct 3, 2007)

I always wondered what the consequences of having non EEC memory was for normal desktop users. Now I know.

They don't use it because of cost, hard to compete against your rival that does not use it, and its a hard sell for the price difference.

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## JohnWill (Oct 19, 2002)

Yep, in days of old, I used ECC in all my systems. Nowadays, it's as scarce as hen's teeth, and many motherboards don't support it if you manage to find the memory.


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## DaveBurnett (Nov 11, 2002)

I had some a couple of months ago.
I had two 2Gb matched sticks of 9 chip HP memory rated 2.3.3.6.
The machine they were in didn't accept them. Only one of my test bed machines could use them and I got fed up of having to change the BIOS every time I tested Non EEC memory so I put them on eBay. They sold for less than half the normal price of memory.


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## Rich-M (May 3, 2006)

I have always found Ecc memory to be considerably more expensive than Non-Ecc and more quickly corruptible since the advent of ddr ram and after. I got so sick of sending it back to Kingston and Corsair after a year or so I quit using it.


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## Elvandil (Aug 1, 2003)

I have a really hard time subscribing to this medieval, vaguely organic, idea of "bit-rot". In fact, I doubt very much that the vast majority of these errors have any practical consequence. It seems people love that "rotten apple spoiling the barrel" analogy with nothing to back it up. There are redundant systems and error-checking going on all the time. It seems that the splash in the pond caused by one errant bit could just as likely fade away as become a tsunami.

And there are also humans involved here. Though a machine running a nuclear plant independently could cause major problems before errors were caught, the small office computer is not likely to sell apples at $10,000 each for too long before the error is noticed by someone and corrected.


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## DaveBurnett (Nov 11, 2002)

> And there are also humans involved here. Though a machine running a nuclear plant independently could cause major problems before errors were caught, the small office computer is not likely to sell apples at $10,000 each for too long before the error is noticed by someone and corrected.


Surely it is more likely that the human will sell them at the wrong price !!!!


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## zx10guy (Mar 30, 2008)

ECC memory is still in wide use in servers and memory subsystems like in RAID controllers.


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## JohnWill (Oct 19, 2002)

zx10guy said:


> ECC memory is still in wide use in servers and memory subsystems like in RAID controllers.


Correct, I guess they figure they can charge extra for it there. 

FWIW, I don't understand the comment about the memory not being compatible, since ECC memory simply adds a bit on otherwise unused pins on the module. I've stuck ECC memory in motherboards that don't support it, it's never been a problem, you just don't use the extra bits. Check the JEDEC standards for DDR and DDR2 memory, ECC won't affect use in devices that don't support the capability.


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## zx10guy (Mar 30, 2008)

JohnWill said:


> Correct, I guess they figure they can charge extra for it there.
> 
> FWIW, I don't understand the comment about the memory not being compatible, since ECC memory simply adds a bit on otherwise unused pins on the module. I've stuck ECC memory in motherboards that don't support it, it's never been a problem, you just don't use the extra bits. Check the JEDEC standards for DDR and DDR2 memory, ECC won't affect use in devices that don't support the capability.


My memory tech knowledge has been a bit rusty lately as I haven't kept up with a lot of the tech/lingo. But I think ECC memory also tends to be buffered too. Not a lot of desktop PC motherboards are compatible with this type of configuration. I have tried using server grade memory in desktops without success.


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## JohnWill (Oct 19, 2002)

Actually, all of the ECC memory I ever used was unbuffered, it comes in both flavors. Of course, since many server class systems use buffered memory, it's obviously available that way.

I did a search for ECC memory, and it's not that easy to find anymore.  However, unbuffered is still around:

http://www.newegg.com/Product/Produ...0144153&cm_re=ecc_ddr2-_-20-144-153-_-Product

http://www.newegg.com/Product/Produ...0134893&cm_re=ecc_ddr2-_-20-134-893-_-Product

If you need registered memory, that's around too.

http://www.newegg.com/Product/Produ...0145219&cm_re=ecc_ddr2-_-20-145-219-_-Product


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## DaveBurnett (Nov 11, 2002)

I just did a quick search, and the consensus seems to be that REGISTERED and BUFFERED are the same thing as a Rose.
A quick way to tell if a memory stick in you hand is ECC or not is to count the number of memory chips.
If it is 3,6,9, or 18 it is ECC.
If it is 2,4 8, or 16 it is Non ECC


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## JohnWill (Oct 19, 2002)

Yep, *Registered* or *Buffered* are synonymous when it comes to memory module descriptions.


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## loserOlimbs (Jun 19, 2004)

JohWill, I guess you can blame me for your ECC finding problems. When ECC for desktops was plentiful, I advised desktops users to save money and get better performance as well as less headaches by going non-ECC... I guess they listened and left the ECC for server platforms like the XEONs and Opterons.


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## JohnWill (Oct 19, 2002)

You're right you scoundrel, you shouldn't have done that!


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