# ECC vs non-ECC RAM



## Tegal (Feb 11, 2005)

I have an old mobo, MSI K7T Turbo 2, which takes pc133 which I know is ancient.

However my question is this - what is the practical difference between ECC RAM and non-ECC RAM? I know that ECC provides error checking and non-ECC doesn't, but also that the majority of home PC's use non-ECC coz it's faster and they don't need the error checking functionality.

So far as i can gather I can use ECC in my system and it'll just ignore the error checking bits. But i also know that ECC runs slower than non-ECC, is this true even on a mobo that doesn't support the ECC function? What sort of speed difference are we talking about anyway?

Price wise ECC seems to be cheaper than non-ECC on places like Ebay.

Thanks
Tegal


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## Frank4d (Sep 10, 2006)

Installing ECC RAM in a motherboard designed for non-ECC RAM will usually cause it to not boot. And the same the other way.


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## JohnWill (Oct 19, 2002)

Actually, installing ECC memory in a non-ECC board will simply run without ECC. The extra memory bits are simply ignored. However, I've never seen a case where it won't boot in that configuration. FWIW, I use ECC memory whenever practicable, since it's just one more bit of extra reliability.


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## Rich-M (May 3, 2006)

Just don't mix Ecc and non- Ecc...that is when it won't boot.


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## erick295 (Mar 27, 2005)

I wouldn't use ECC on anything but a server... the chances of any errors occurring in RAM are close to none, especially if you have _good_ RAM... however, on a server, even one error is a BIG problem, because the RAM is used a lot, and server crash = downtime. For home or workstation use, though, it just adds expense (normally) and makes it marginally slower, with no real gains to speak of.

Yes, it should run on a non-ECC board, but personally I would just spend the extra and get non-ECC to make a better match.


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## Tegal (Feb 11, 2005)

Does the ECC still perform it's error checking on a non-ECC board? i.e. will it still be that tiny bit slower than it's non-ECC equivalent (because of the error checking) or can it detect that it's on a non-ECC board and disable the error checking? This is a q for information only, on PC133 I doubt it will make a significant difference in performance.

Reason I ask is that one stick of 512Mb PC133 ECC ram is going cheaper than non-ECC on Ebay, it seems to be less popular, but before I buy one I want to know what I'm getting.

Thanks guys, this is really helpful.

Tegal


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## MaverickUK (Nov 30, 2006)

If you use an ECC RAM module and install it on a non-ECC motherboard, the result will be a non-used bit on the RAM. The computer will use the RAM as any other 'normal' module and will execute and transmit (minus the one extra bit) in exactly the same way as non-ECC RAM would on a non-ECC motherboard.


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## JohnWill (Oct 19, 2002)

Rich-M said:


> Just don't mix Ecc and non- Ecc...that is when it won't boot.


If you configure the BIOS for non-ECC, it'll boot fine. It'll also work if the first bank is populated with non-ECC memory. However, if the first bank has ECC memory, and the second bank has non-ECC memory, you will normally get a POST memory error.


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## JohnWill (Oct 19, 2002)

erick295 said:


> I wouldn't use ECC on anything but a server... the chances of any errors occurring in RAM are close to none, especially if you have _good_ RAM...


So, all the memory errors we hear about here are actually statistically impossible?


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## JohnWill (Oct 19, 2002)

Tegal said:


> Does the ECC still perform it's error checking on a non-ECC board? i.e. will it still be that tiny bit slower than it's non-ECC equivalent (because of the error checking) or can it detect that it's on a non-ECC board and disable the error checking? This is a q for information only, on PC133 I doubt it will make a significant difference in performance.
> 
> Reason I ask is that one stick of 512Mb PC133 ECC ram is going cheaper than non-ECC on Ebay, it seems to be less popular, but before I buy one I want to know what I'm getting.
> 
> ...


The memory will work just fine, and it'll be just as fast as the non-ECC memory when you're running it as non-ECC memory. Note that you "may" have to specify non-ECC memory in your BIOS, depending on the specific memory controller and how it initializes memory.


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## erick295 (Mar 27, 2005)

JohnWill said:


> So, all the memory errors we hear about here are actually statistically impossible?


lol

Like I said, _close_ to none, especially _if_ you have good RAM 

When people buy $10 specials on eBay and pair them with a $25 motherboard, yeah, they're more likely to have problems... personally, I buy good stuff, and I have never, not even one time in my entire life, had a single crash due to a memory error. Neither has anyone I've built a machine for.


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## Tegal (Feb 11, 2005)

When it comes to quality RAM it's a case of once bitten twice shy. Bought some budget RAM once, lots of trouble. Replaced it with slightly more expensive Kingston economy RAM and been running sweet as a bell since!

Kingston is my first choice for RAM, you can get it on ebay if you don't mind waiting for it to come round. Anyone used Crucial RAM? My impression is that they are comparable to Kingston.

That said, as I was re-installing my system on the MSI K7T Turbo 2, with 1x 256Mb Kingston PC133 and 1x 128Mb Kingston PC133 I was getting some errors when the install files were not copied. Remove one stick and problem solved so definitely RAM, but memtest86 didn't find anything. So running XP on 256 only right now. Had a problem with the old system where it would lock for no apparent reason, suspecting RAM problem now.


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## JohnWill (Oct 19, 2002)

I've had memory of almost every brand fail at one time or another. I currently have a Kingston 512mb DDR2 sitting here waiting to be returned. Memory can and will fail at some point, ECC is just another tool in the reliability toolbox. If memory never fails, what's the point of putting ECC memory in servers?

I will also point out that transient errors are a larger issue than outright failures, and ECC memory neatly solves this issue too.


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## erick295 (Mar 27, 2005)

JohnWill said:


> I will also point out that *transient errors* are a larger issue than outright failures, and ECC memory neatly solves this issue too.


Transient errors are exactly what I'm talking about... even ECC won't do you any good if the RAM is bad. It only protects against minor single-bit errors. Those kinds of errors are more common in cheap RAM. I'm not talking about memory failure at all.

Why use it in a server? Like I said, downtime = bad. When you're running lots of RAM under high stress 24/7, your chances for errors increases. It only takes one to crash the system, bringing the server down until it's rebooted.

You hardly need ECC memory to read your email for two hours a day, lol, unless you're willing to put up with the speed loss to protect yourself against the 1 in 1,000,000 chance that your computer is going to lock up because of a memory error maybe once or twice in its entire life 

(unless you buy cheap RAM and motherboards, in which case, good luck...)


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## erick295 (Mar 27, 2005)

I guess what I'm saying is, you don't build a paper airplane to the same tolerances as a 747... and a home computer is a toy compared to a server


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## Tegal (Feb 11, 2005)

erick295 said:


> ... and a home computer is a toy compared to a server


TOY!! My home computer is just a TOY!?!  
An Englishman's computer is his virtual castle! (And it can be considerably more impressive than his home).

But to sum up - so long as the mobo can handle ECC RAM, even if it doesn't use the error checking facilities, and assuming that price is equal, there is no real reason to pick one over the other. Both should work, but the advanced capabilities of one will just be ignored. Just avoid mixing the two!


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## JohnWill (Oct 19, 2002)

erick295 said:


> I guess what I'm saying is, you don't build a paper airplane to the same tolerances as a 747... and a home computer is a toy compared to a server


I make my living with the computer, and it's used 8-10 hours a day. Many other people are in the same boat. I guess if you only play games on your computer, reliability isn't all that important, it is to me.


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## Tegal (Feb 11, 2005)

Ok, maybe this is moving away from the original topic a bit, but is there any way to know what RAM cl the mobo will support? I've been looking thru the BIOS settings and i can adjust the DRAM Timing by SPD, and the CAS Latency.

Considering the following 2 bits of RAM:
KVR133X64C2/512
KVR133X64C3/512

Both Kingston, only difference is the CL. Now my mobo says that for the CAS Latency I can use Auto, 3 or 2. It says 3 is more stable but 2 will enhance system performance. With this in mind do I have to go for the C2 RAM to use a CAS latency of 2? Will C2 also run with latency of 3? Am I asking the right questions?

How does the DRAM relate to the FSB (if at all)? And won't upping the clock on the RAM have a knock on effect with the processor?

I'm not really into over clocking, not yet anyway  but when the difference is £2-3 it's probably worth shelling out the difference to squeeze the most out of what is an ageing system.

Thanks


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## JohnWill (Oct 19, 2002)

You can slow things down, just don't run them faster than the ratings if you want maximum reliability. Also, you'll probably want to check all the memory specifications and run at the slowest speed for the installed memory.


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