ECC is technology that allows computers to correct memory errors. The most popular type of ECC used in memory modules is single-bit error correction. This enables the detection and correction of single-bit errors within a byte, or 8bits of data. It will also detect two-bit and some multiple bit errors, but is unable to correct them. Take the most common single bit error correction for example. For each byte of data sent across the memory bus, a check-bit is generated by calculating that byte of data using an Exclusive OR algorithm.
This check-bit will be stored in a separate memory chip. That is why memory modules with ECC capabilities have nine memory chips on each side, rather than the eight chips per side often seen with non-ECC memory modules. The system will use the check-bit to check if the data is correct, and correct the single-bit error if there is one. The check-bit will be transferred together with the original byte of data.
Remember only 64 bits out of the 72 bits of data are counted for bandwidth and application usage, the other 8 bits are all check-bits, so the effective bandwidth of ECC and non-ECC memory is identical. There are two major causes of the so-called "soft" errors: Naturally occurring radioactive isotopes which emit alpha particles High energy cosmic rays from supernovas Both of these events can change the value of data stored in a memory chip. These errors are called "soft" errors because they can be repaired by correcting the value of the memory bit, which is exactly what ECC does.
Chances for a single-bit soft error occurring are about once per 1GB of memory per month of uninterrupted operation. Since most desktop computers do not run 24 hours a day, the chances are not actually that high. For example, if your computer with 1GB of memory runs 4 hours a day, the chances of a single-bit soft error happening when your system is running is about once every six months. Non-ECC also called non-parity modules do not have this error-detecting feature.
Any chip count not divisible by three or five indicates a non-parity memory module. Using ECC decreases your computer's performance by about 2 percent.
All rights reserved. I currently use 4xMB unbuffered-ECC, but wish to install some cheaply available ebay ecc-registered before I upgrade to a new system. Not a Dell fan but your statement was completely unfounded. From Sandy bridge through to Ivy Bridge, Unbuffered ECC compatibility is dependent on the motherboard chipset and actual wiring to the ram socket.
It is no longer based on the processor. If you take a look at the technical specs for the Sandy Bridge processors you will see this statement. Only the C supports unbuffered Dimms i. Sandy Bridge server PCHs were restricted so they would fail to boot with an i5 or i7 which effectively meant you could not run an i5 or i7 on a motherboard with ECC support. I believe this is where a lot of the confusion comes from.
That and Intel refusing to state the fact clearly. Thank you very much for this useful article. Do you know anyway to get this info? Wish me luck.. Does your motherboard chipset support ECC? Do you have the correct type of ECC ram for your mobo udimm vs rdimm? Can someone explain which memory can be easily extended??
Which memory allows me this ugrade?? Hello from May of ! Still the best comparison of ECC and unbuffered I could find. Therefore registered memory is usually only used for systems where a lot of RAM is required and system reliability is important, such as servers. Most registered RAM also features ECC error-correcting code which can detect and correct the most common kinds of internet data corruption.
Most memory used in consumer systems is known as unregistered or unbuffered memory and is considered to be the conventional form of RAM. This will be a number, either 3 or 1. Allow Cookies. Registered and Unregistered Memory - What's the Difference?
December 11,
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