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BabakN

Guest
Original poster
I'm getting ready to buy an iMac 24" 2.8 GHz, but am confused about what speed RAM upgrade to get.

The specs say that the processor has a 1066 MHz Front Side Bus, but the memory that's installed on the machine is only 800 MHz. Not sure why they do that!

My question is, can I buy third party memory that's faster than 800 MHz and safely run in on this machine?

Thanks,
Bobby
 

barnettebw

macrumors newbie
Mar 20, 2008
15
0
nope

Unfortunately the iMac, as do all other Macs (exlcuding the Mac Mini, which still runs 667 MHz RAM I believe) run 800 MHz RAM.

The Frontside Bus of 1066 MHz does not imply that 1066 MHz RAM can be used. The connection between RAM and logic board on the new iMac bottlenecks at 800 MHz.

The faster Frontside Bus is instead used in conjunction with other system components (i.e., I/O, really speedy hard drives, etc.).
 

gehrbox

macrumors 65816
Jul 5, 2007
1,040
0
Charleston,SC
Unfortunately the iMac, as do all other Macs (exlcuding the Mac Mini, which still runs 667 MHz RAM I believe) run 800 MHz RAM.

The Frontside Bus of 1066 MHz does not imply that 1066 MHz RAM can be used. The connection between RAM and logic board on the new iMac bottlenecks at 800 MHz.

The faster Frontside Bus is instead used in conjunction with other system components (i.e., I/O, really speedy hard drives, etc.).

The latest MacBook Pro's (early 2008) still use PC2-5300 (667MHz). Ditto for the MacBook and MacBook Air.

Read the following info to gain a better understanding of how DDR2 memory and the FSB speeds integrate.

http://en.wikipedia.org/wiki/Front_side_bus
http://en.wikipedia.org/wiki/Double_Data_Rate
http://en.wikipedia.org/wiki/DDR2
http://en.wikipedia.org/wiki/Memory_divider
http://guides.macrumors.com/Understanding_Intel_Mac_RAM
 
B

BabakN

Guest
Original poster
Thanks!

Thanks for the education! Makes sense.

And yes, the 10066 MHz typo is a good one!
 
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