SERVER RAM

ECC Registered Server RAM-

Server memory is generally ECC Registered (buffered). There are extra chips on the module that provide error correction and data checking functions. It is easy to spot ECC Registered Server RAM by looking at the chips on the module.

While desktop memory usually has eight chips per side, server memory has 9 large or 18 half-size chips per side, plus two or three smaller "register" chips. The 9th (and 18th) DRAM chips provide the error 

correction function, and the additional "register" chips hold the data for one clock cycle (ie act as "buffers") to increase the reliability of high-speed data access.

Unless your machine specifically supports ECC Registered memory your machine will not function correctly and may not even boot with this type of memory installed.

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ECC Unbuffered RAM

Many workstation computers and some servers use ECC unbuffered RAM. ECC unbuffered RAM looks similar to standard desktop memory, but instead of 8 chips per side it has 9 chips per side. The 9th chip handles the error correction function in machines that support ECC memory.

It can be confusing because server RAM is often referred to as simply "ECC RAM", but ECC unbuffered is not the same as ECC registered. If your machine uses DDR2, DDR, or SDRAM and requires ECC unbuffered memory, in most cases ECC registered is not compatible. Server motherboards that use DDR3 memory can often use either ECC unbuffered or ECC registered, however you cannot use both types in the same machine at the same time.

To be absolutely certain what memory type you are running, look at the memory currently installed in your machine and check your product manual.

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ECC Fully Buffered Server RAM 

FB-DIMMs (aka fully buffered) are a type of ECC RAM which use an Advanced Memory Buffer (AMB) between the memory controller and the memory module. The notch on FB DIMM memory is offset to prevent these modules from being installed in systems which use standard DDR2 RAM. Future development of this memory type is uncertain. We do not carry FB-DIMMs at GeeK NoiZe because there are no benchtop memory testers available which can test this type of module.

COMPUTER MEMORY TYPE

Desktop RAM

Desktop personal computers require Non-ECC Unbuffered RAM. There can be exceptions, so use the information below to determine what memory type your machine is currently running.

Non-ECC unbuffered memory usually has 8 chips per side and can be single sided or double sided. Low density dual channel desktop RAM commonly has 8 chips on both sides.

Please note that server RAM does not work in most desktop computers. Server RAM is ECC Registered, and desktop RAM usually needs to be Non-ECC and Non-Registered (unbuffered).

Desktop SDRAM - 168 pins, 2 notches at the bottom (PC100 or PC133)

Desktop DDR - 184 pins, 1 notch at the bottom (PC2100, PC2700 or PC3200).

Desktop DDR2 - 240 pins, 1 notch at the bottom. 

(Note-The notch in DDR2 RAM is in a slightly different location to prevent it from being installed in machines that require DDR RAM. DDR2 is not backwards compatible with DDR1.)

Desktop DDR-3 - 240 pins, 1 notch at the bottom. 

(Note-The notch in DDR3 RAM is in a different location to prevent it from being installed in machines that require DDR or DDR2 RAM. DDR3 is not backwards compatible with DDR2.)

Laptop RAM

Laptop computers require Non-ECC Unbuffered SODIMMs. The module size is physically about half as long as desktop memory.

Laptop SDRAM - 144 pins (PC100 or PC133).

Laptop DDR (DDR1) - 200 pins (PC2100, PC2700 or PC3200).

Laptop DDR2 - 200 pins 

(Note-The notch is in a slightly different position to prevent DDR2 RAM from being installed in DDR1 laptops. DDR2 is not backwards compatible with DDR1.)

Laptop DDR3 - 204 pins
(Note-DDR3 is not backwards compatible with DDR2 or DDR1.)

NOTE--A RAM Timeline

1997 (SDRAM) PC66 SDRAM 66MHz
1999 (RDRAM) RDRAM 800MHz
2000 (DDR-SDRAM) DDR SDRAM 266MHz
2004 (DDR2-SDRAM) DDR2 SDRAM 533MHz
2007 (DDR3-SDRAM) DDR3 SDRAM 1066 - 1333MHz

Different between Server RAM and Desktop RAM

The memory in a server is expected to be fast, and is called ECC memory. ECC stands for error correcting code memory. This memory system tests and corrects any errors in memory without the processor or user being aware of it. The error correcting code generates a checksum when data is loaded in memory, and when it unloads, the checksum is recomputed and if an error is detected it is automatically corrected. This ensures that the data passed in the server is correct. 

All desktop, laptops, and tower computers use different types of memory classed on their speed and structure. They are known as SDR, DDR, DDR2, etc, and as the personal computer world has seen the personal computers getting faster and faster, the memory speeds have also been enhanced over time. 

If you put a high-speed memory in a slow speed processor machine, it will probably burn out and the same rule applies vice versa. The memory speed and the processor speed have to be synchronized to work properly. 

In desktop computers, you may have had incidents of a memory chip getting defective, or the computer gives a memory-addressing fault. This never happens in a server machine. Server machines are supposed to be zero-fault tolerance machines. The applications that are supposed to perform cannot afford any downtime. 

High-end servers have a very robust architecture, as they are used to perform very specific jobs. Therefore, they are built such that the possibility of a fault occurring is minimized. In case, a fault does occur, the machine will not crash or the application will not stop. Therefore, a proper server machine does have different memory from a non-server machine. Very few people are aware of this, as the environments in which they work don't use high-end servers.

NOTE- ECC (which stands for Error Correction Code) RAM is very popular in servers or other systems with high-value data as it protects against data corruption by automatically detecting and correcting memory errors. Standard RAM uses banks of eight memory chips in which data is stored and provided to the CPU on demand. ECC RAM is different as it has an additional memory chip which acts as both error detection and correction for the other eight RAM chips.