What is ECC Memory?

[KrazieKlown]

I have resently purchased a Tyan Tiger MP Mobo (dual processor)

The manual said it needs ECC registered memory

I was wondering what Registered means. I know ECC is Error Correction but can I just get ECC mem or do i need both ECC and Registered? or are they the same thing?

[Richard Cranium]

ECC is Error Correction memory usually reserved for servers, which seems as if the dual processor board you've gotten was ment to be.

ECC is a bit slower also due to the extra cycles needed to double check itself.

Registered is another term totally, forgot exactly what it means.

Check at Crucials site, they have great guides.

What does "registered" SDRAM mean?

Q.Is all registered SDRAM also ECC?

A. Yes and no. Registered SDRAM does not necessarily have to be ECC. However, at Crucial, we've found that our customers who purchase registered SDRAM also want ECC. As a result, all of the registered SDRAM we sell at Crucial.com is also ECC.

[MegalosSkylaki]

Don't ECC's have an extra chip on them to do the correctuion--or is that "parity" memory.....

[Ruahrc]

If I remember right- didn't Registered memory also have a different form factor so that you didn't accidently put unbuffered in a registered slot or vice versa?

It was something really small like moving the notch on the DIMM stick 2-3mm to the right or left. Enough to make them un-interchangeable though.

Ruahrc

[Thud]

I think you can use normal, non ECC, non-registered DDR, as long as you only use slots one and two:

Do note that Tyan is only supporting the use of two DDR slots with standard memory and that you must have registered memory to use the third and/or fourth DDR slot.

http://www.amdmb.com/article-display...D=114&PageID=2

I seem to recall reading the same thing in a review at Anandtech as well.

~Edit: And welcome to TechIMO! I also have one of those boards on it's way....should kick butt.

[Polygon]

Originally posted by MegalosSkylaki
Don't ECC's have an extra chip on them to do the correctuion--or is that "parity" memory.....

Yes, ECC has an extra chip.

[boffola]

DDR and SDRAM can be unbuffered or registered. EDO and FPM can be buffered or unbuffered. Buffered modules contain a buffer to help the chipset cope with the large electrical load required when the system has a lot of memory. Registered modules do not have a buffer but do contain a register that delays all information transferred to the module by one clock cycle. Buffered and registered modules are typically used only in servers and other mission-critical systems where it is extremely important that the data is properly handled.

[boffola]

If you already have a PC and are unsure which type you have, count the number of small, black, IC chips mounted on one of your existing DIMMs. If the number of chips is evenly divisible by three, then you need ECC. If the number of chips is NOT evenly divisible by three, you have non-parity memory.

If you are building a PC and deciding which type to use, the following guidelines should help. If you plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity.

ECC (Error Checking and Correcting) performs "double bit detection and single bit correction." This means that if you have a single bit memory error, the chipset and memory will find and repair the error on the fly without you knowing that it happened. If you have a double bit memory error, it will detect and report it. Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.

boffola