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It is different from what Crucial's memory adviser recommends (accessed either via the buy.com site or Crucial's site).

Recommended: http://www.crucial.com/store/mpartspecs.aspx?mtbpoid=2DDAFA5FA5CA7304
What you ordered: http://www.crucial.com/store/partspecs.aspx?imodule=CT3KIT51272BB1067

The most apparent difference appears to be that the recommended memory is unbuffered while what you ordered is registered. Will it work? Dunno. If it does work, it will be slower.

How much of a performance hit would I take with it??
 
""Registered" is a means of "Buffering" the memory in SDRAM. This means that the clock signal is boosted across the entire array of memory chips so that the computer sees a clean sharp clock signal instead of a weakening clock signal as it progresses along the length of the memory path. Registered memory must be supported by the system board and cannot be mixed with "Unbuffered" modules. You must have only Registered memory to use Registered memory. This is a further means of eliminating the possibility of errors when reading the data in memory and is used when the data returned from memory is extremely critical, such as in scientific or financial calculations where the integrity of the data is CRITICAL. It also allows a module to be built using more chips, allowing for larger capacity modules to be made."

Found that, apparently the RAM will be a tad slower, because it is built for integrity in servers and not commercial use. Such a shame, that was a fantastic price on those modules. Oh well, back to eBay I go!
 
Are you sure it works? The Mac Pro only accepts 1.5V modules. 90%+ Tri-channel ddr3 sets are 1.65V. That's why its fairly difficult to find the right ram. Sure 1.65V ram would work, but its not rated to run at 1.5V (which it will have to), and thus you are risking memory stability.

Or if its 1.5V then that's a VERY good deal. The problem is that higher voltage ram is always cheaper.

EDIT: Just checked, these are 1.5V modules. You got a very good deal, as their msrp is $539 according to Crucial's website. Here: http://www.crucial.com/store/partspecs.aspx?IMODULE=CT3KIT51272BB1067

BTW, don't rush so quick to make a purchase next time without fully knowing the specs. You could have accidentally ordered $375 of memory paperweight.
 
I forgot to mention, but Mac Pro's need RAM with an Apple certified thermal sensor.

If you buy RAM without a thermal sensor, your fans will spin wildly at full RPM because it thinks you RAM is overheating.
 
I forgot to mention, but Mac Pro's need RAM with an Apple certified thermal sensor.

If you buy RAM without a thermal sensor, your fans will spin wildly at full RPM because it thinks you RAM is overheating.

Can anyone verify this? I have seen many people go with 3rd party RAM to no ill effect.
 
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