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>> "and includes the latest four-channel ECC DDR3 memory running at 1866 MHz to deliver up to 60GBps of memory bandwidth.* " - It should be "running at 933⅓ MH

>> "and includes the latest four-channel ECC DDR3 memory running at 1866 MHz to deliver up to 60GBps of memory bandwidth.* " - It should be "running at 933⅓ MHz". A DDR3-1866 module is 933⅓ MHz, 1866⅔ MT/s, ~15GB/s. They have quad channel DDR3-1866. (If you disagree - check the DDR3 spec. Article at apple.com is simply wrong in stating running at 1866 MHz I know it is a minor point, but when you are listing specs, you have to be precise.) - Update: sorry, saying "running at 1866 MHz" is Ok. I stand corrected.

wtallis 13y ago
Absolutely nobody uses that scheme for referring to memory speeds. Everybody uses the effective clock speed, and there's really nothing technically wrong about labeling that with MHz, since Hz isn't restricted to referring to only sinusoidal clock signals. If you're going to be pedantic, then you ought to make clear when you're referring to the memory clock speed or the I/O clock speed or the transfer rate. For anyone who is interested only in using a memory module and not implementing the memory bus, 1866 is the only number that matters.
- pslam 13y ago
  Hz refers to the number of cycles per second. Everybody uses this as the effective transfer clock, but hey, everybody is wrong. It's correct to use MT/sec instead, but you're right that it's being pedantic and it's unlikely to confuse anyone who really did care. On the other hand, it does stink of specmanship to quote the doubled frequency. I would have hoped a Pro spec machine would rise above that kind of thing.
  - sliverstorm 13y ago
    The doubled frequency is just the way the market works. It is actually kind of nice when you are trying to compare sticks that are double sided vs. sticks that are single sided and actually run at the listed frequency.
  - mehrdada 13y ago
    Hz is just 1/sec. If you want to be technically correct, don't add any implicit meaning to it. Frequency is the rate of something happening per unit of time. That "something" can be "number of data transfers" or "number of clock cycles" or "number of times a ball hits the floor". The frequency of all of those can be measured in Hz. You should be clear about what quantity you're measuring, but the unit is Hertz nevertheless. (And MT/sec is really "some unit-less quantity/sec", so it can be accurately called MHz.)
zdw 13y ago
You can also add the dual naming scheme that gives us gems like "PC3-14400" where the latter number is the MBps of bandwidth or something similarly confusing to 95% of people, myself included.
- sliverstorm 13y ago
  "PC3-14400" wouldn't be half so bad if there wasn't also "PC3-14440", "PC3-14444", "PC3-14000", and maybe "PC3-14402" depending on which manufacturer you are buying from. To make things even more dandy, they aren't interchangeable.

wtallis 13y ago

Absolutely nobody uses that scheme for referring to memory speeds. Everybody uses the effective clock speed, and there's really nothing technically wrong about labeling that with MHz, since Hz isn't restricted to referring to only sinusoidal clock signals. If you're going to be pedantic, then you ought to make clear when you're referring to the memory clock speed or the I/O clock speed or the transfer rate. For anyone who is interested only in using a memory module and not implementing the memory bus, 1866 is the only number that matters.

pslam 13y ago
Hz refers to the number of cycles per second. Everybody uses this as the effective transfer clock, but hey, everybody is wrong. It's correct to use MT/sec instead, but you're right that it's being pedantic and it's unlikely to confuse anyone who really did care. On the other hand, it does stink of specmanship to quote the doubled frequency. I would have hoped a Pro spec machine would rise above that kind of thing.
- sliverstorm 13y ago
  The doubled frequency is just the way the market works. It is actually kind of nice when you are trying to compare sticks that are double sided vs. sticks that are single sided and actually run at the listed frequency.
- mehrdada 13y ago
  Hz is just 1/sec. If you want to be technically correct, don't add any implicit meaning to it. Frequency is the rate of something happening per unit of time. That "something" can be "number of data transfers" or "number of clock cycles" or "number of times a ball hits the floor". The frequency of all of those can be measured in Hz. You should be clear about what quantity you're measuring, but the unit is Hertz nevertheless. (And MT/sec is really "some unit-less quantity/sec", so it can be accurately called MHz.)

zdw 13y ago

You can also add the dual naming scheme that gives us gems like "PC3-14400" where the latter number is the MBps of bandwidth or something similarly confusing to 95% of people, myself included.

sliverstorm 13y ago
"PC3-14400" wouldn't be half so bad if there wasn't also "PC3-14440", "PC3-14444", "PC3-14000", and maybe "PC3-14402" depending on which manufacturer you are buying from. To make things even more dandy, they aren't interchangeable.