What is Registered RAM?

[JaiKnight]

What does it mean for a RAM chip to be "Registered"?

 

[medic]

Buffered
This means that buffer chips serve as intermediaries between the outputs of the controlling chip sets and the memory chips on the modules. Buffers were used on Fast Page and EDO modules to drive more memory chips in server applications. The controlling chip sets were not able to drive huge memory arrays directly. An example is the SC450NX and AD450NX servers manufactured by Intel. These servers can have up to 16 DIMM modules, each with up to 36 chips for a total of 576 memory chips. The NX chip set cannot directly drive 576 memory chips. Instead, the NX chip set drives a pair of buffers on each module. Each buffer pair drives the 36 memory chips on the module.

Registered
A much faster version of buffered, used on synchronous modules. Each register has the system clock connected to it and transfers signals from the input of the register to the output on the rising edge of the system clock. 2 registers are used on PC100 and PC133 modules with 128 Mbytes of SDRAM (9-128 Mbit chips). Up to 3 registers are used on PC100 and PC133 modules containing 256 or 512 Mbyte modules or 1 Gbyte modules. These registers drive from 18 to 36 SDRAM's per module.
What this means is that over these larger modules the data is written to and read from the module correctly and in total, nothing is lost in the transfer over such large module sizes. Usually registered modules are 256 meg and above.
From:
Here:

 

[hans007]

also athlon boards dont support registered. I found out the hard way.

 

[AMB]

I think that the Kx133 and the KT133 supports ECC?

 

[dszd0g]

From what I hear (though I have not seen benchmarks) registered is slower than normal SDRAM. However, on motherboards that support registered you generally need to use registered memory to hit their maximum memory size. Registered is also more expensive. Registered and non-registered memory will not work together in the same system generally.

ECC has to do with error correction (fixing single bit parity errors) and to the best of my knowledge has nothing to do with registered memory.

 

[JaiKnight]

Thanks for the info everybody!

 

[downhiller80]

. . . a waste of money

 

[hans007]

yeah i've run the kx133 and kt133 boards with ecc. But when i tried a registered ECC on and irongate it didnt work. I've heard some via (apollo pro 133/a, kx/t133) boards support it, but all the ones i've had dont.