RAM question: 32x72 and 64x64??

Malladine

Diamond Member
Mar 31, 2003
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What does that mean?

Eg from newegg: "CRUCIAL MICRON 256MB 32x72 PC 2100 DDR RAM - OEM"
 

Lonyo

Lifer
Aug 10, 2002
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32x72 means the RAM has 72 data bits.
Motherboards have 64bit RAM slots, for, naturally, 64bit memory.
Newer boards can have dual channel 128bit RAM, which combines 2 64 bit channels to make a 128bit channel, doubling the bandwidth.
That's not really relevant though.

That RAM has 72 bits (not 64), so it's not like regular RAM.
Most RAM has 8 little chips on each side of the stick, which each have a bit of memory on them, which when combined gives the stick its RAM (256MB in this case).
A stick with ?? x 72 has 9 chips on the side, not the usual 8.
64/8 is 8
72/8 is 9
This extra piece on the RAM is for error checking and correcting (ECC), to make sure nothing goes wrong with the data that passes through the RAM.
For most users ECC RAM (72 bit) is not needed, and it doesn't function on all motherboards, as they do not support it. It is mainly used in servers which need to make sure that nothing goes wrong, including errors in any data that passes through the RAM.
ECC RAM also slows down performance slightly, and holds a price premium over normal RAM (64 bit).
You should only really think of ECC RAM if you have a motherboard with 4 RAM slots that you want to fill all of, or if you are looking to have probably 2 gigabytes or more of RAM in your system.
Other than that, you should go for a 256MB 32x64 stick, as it will be cheaper and there will not be any other difference for you.
 

Malladine

Diamond Member
Mar 31, 2003
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Wow, awesome explanation Lonyo. Many thanks. Going to write that down in my txt file of lore. :)

Thanks to you too Jack ;)
 

Whitedog

Diamond Member
Dec 22, 1999
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Nice Lonyo. Though there is a bit more too it.

Parity or ECC (there is two different kinds) can have either 9 or 18 chips.

ECC RAM, ALL chips will have the same "part number". If you have an Odd chip with a different part number, it is a Parity chip (also known as registered memory).

Parity or ECC ram has 9 bits per byte instead of 8, the extra bit is used for error correction in ECC and tranmission verification in Parity.

30 pinn simms are:
*x8 = non-parity
*x9 = parity or ECC

72 pinn simms are:
*x32 = non-parity
*x36 = parity or ECC

DIMMS are:
**x64
**x72

....and so on...

Some mobo's REQUIRE you to have ECC or Parity ram. They won't work without them. (mainly server mobo's)

Some can use either... a simple BIOS setting to tell it which kind you have.

Most common mobo's cannot use ECC or Parity. ALTHOUGH... you can still put the ram in the board. It will just treat it like non-parity or ecc ram. I don't believe there is any kind of performance issue doing this, the system just ignors the extra chip... ?

ECC and Parity was designed way back when Memory was Crap as far as reliability. With todays memory being so well made, the reliability is so good the need for ECC and Parity isn't as important.
 

buleyb

Golden Member
Aug 12, 2002
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Originally posted by: Whitedog
ECC and Parity was designed way back when Memory was Crap as far as reliability. With todays memory being so well made, the reliability is so good the need for ECC and Parity isn't as important.

Well, it is still a good thing for many applications, particularly applications that need assurance of good data. Enterprise systems, or anything that deals with applications that cannot stop, and requires clean data, should use this (ie, real-time systems, safety systems, etc). Its just a level of protection that some systems need (and many still do)

EDIT: But you are right, not needed by the typically gamer :)
 

pm

Elite Member Mobile Devices
Jan 25, 2000
7,419
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ECC and Parity was designed way back when Memory was Crap as far as reliability. With todays memory being so well made, the reliability is so good the need for ECC and Parity isn't as important.
Leaving my computer (with ECC) running for six weeks or so 24x7, it's disconcerting the 2-3 single-bit (ECC corrected) errors that I usually see in the log file.