Buffered and Registered RAM

[wolf550e]

please someone explain those once and for all. i am mixed up. what are those? do we need it? what do we use?

 

[AndyHui]

Expensive stuff....for servers, we don't need it since normal "workstation" use has no benefits.

Registered RAM is a type of ECC RAM, as is buffered (I think...)

 

[JaiKnight]

Try this link for some info: http://www.realtime.bit.net.au/sdram_info.htm

 

[pm]

Registered SDRAM (aka "buffered" SDRAM - the terms are interchangeable when used to describe SDRAM) are intended for workstations and servers. Basically all pins except the data and the clock pins) are buffered through a register. This reduces the loading by "buffering" the address and control inputs. The main advantage is that you can put more than 4 DIMMs on a memory controller - up to 8, IIRC. There's a one clock latency penalty (from the register), but sometimes this can be masked.

ECC SDRAM is a whole different thing. ECC is a type of fault detection/correction circuit that is used to detect and fix memory errors on the fly. Alpha and Beta particle impact ionization in a memory bit can cause a bit flip (0->1 or 1->0) which causes a memory error. With the old parity memory, your system could detect that a bit had bit flipped on memory read, but would then print "Parity Error" and freeze up - which prevents this bad data from being written, but erases all current data. ECC can determine one flipped bit in 64-bits and can detect an error in two bits (which causes a parity error shutdown as before).

Registered memory is definitely intended for servers/workstations or systems with a lot of RAM (>2GB). ECC is argueably intended for anyone who cares a lot about data integrity on their system - which is not necessarily someone on a workstation.

 

[Vegito]

Basically I only get registered ecc for all my servers & workstation,, its a bit more but it's worth it.

It ensures that data level in is data level out, signal strength... but hey, I can't tell..

 

[superbaby]

We lowly monkeys use unregistered DRAMs. Registered/ECC DRAM would break our wallets.

 

[pm]

Actually the price difference is fairly minor if you are buying quality RAM. Based on prices from Crucial.Com (Micron):

SDRAM, PC133 ? CL=3 ? Unbuffered => $95
SDRAM, PC133 ? CL=3 ? Unbuffered ? ECC => $104
SDRAM, PC133 ? CL=3 ? Registered ? ECC => $111

If you are buying the cheap stuff, then this definitely is not the case. Still, IMO if you use your computer for any type of work - even infrequently, then cost is not a good reason for getting non-ECC over ECC.