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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac - New iMac - Memory speed


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touringman

 
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Just ordered a new 24" iMac.

Was gonna get 3rd party Ram upgrade to 4GB but crucial have got two speeds available - 5300 667 and 6400 800 - the latter being very expensive!

Questions
- Any difference in real world performance?
- Any way it can mix two different types?
- 4gb of 5300 667 or 2 gb 6400 800?

Cheers

Tim
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Sennec

 
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Get the 800, it's much faster.
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smurfy

 
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Quote:
Originally Posted by Sennec View Post
Get the 800, it's barely faster.
I fixed your post.
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Sennec

 
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Quote:
Originally Posted by smurfy View Post
I fixed your post.
Ty :')
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technologist

 
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Get the 667. The 800MHz memory won't run any faster at all in an iMac.
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darwinism

 
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Quote:
Originally Posted by technologist View Post
Get the 667. The 800MHz memory won't run any faster at all in an iMac.
I beg to differ:

Quote:
* 2.0GHz or 2.4GHz Intel Core 2 Duo processor, or 2.8GHz Intel Core 2 Extreme processor
* 4MB shared L2 cache at full processor speed
* 800MHz system bus
* 1GB (one SO-DIMM) of PC2-5300 (667MHz) DDR2 memory
* Two SO-DIMM slots support up to 4GB
Taken DIRECTLY from the Apple site, specs of the latest iMac. I'd bet you 100 that the reason Apple load them up with 667 ram, is due to the (currently) prohibitively expensive 800 ram.

Crucial list PC-6400 on their upgrade site for iMac:
http://crucial.com/uk/store/listpart...h%29%20MA876LL

So if it was no faster, then why would they do so?.
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technologist

 
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Quote:
Originally Posted by darwinism View Post
I beg to differ:
[...] I'd bet you 100 that the reason Apple load them up with 667 ram, is due to the (currently) prohibitively expensive 800 ram[....]
Taken DIRECTLY from the Apple (hardware developer documentation) site
http://developer.apple.com/documenta...inkElementID_7
Quote:
The SO-DIMMs must be DDR2-667 (PC2-5300) compliant
Note also the block diagram here:
http://developer.apple.com/documenta...4829-TPXREF101
Which clearly notes that the RAM slots run at 667MHz

Shall I PM you with my address for my 100?
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BlackSheep

 
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WOW!! The last post with the links confused me more than when I started reading the thread. People (well most) by Macs because there simple. Can someone please translate all the technobabble. I thought the 800MHz front-side bus meant you could run the faster 800MHz ram. If so does it actually make a difference?
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christm

 
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Quote:
Originally Posted by smurfy View Post
I fixed your post.
lol. i dont know the difference. but i would assume there isnt much difference between the two speeds.
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iNick

 
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You can mix the speeds, BUT, if you have two different speeds of RAM in a computer, all the RAM will be accessed at the lower of the two speeds. That said, Id go for the cheaper of the two cause you won't notice the difference.
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As technologist stated, the new iMac runs at 667 Mhz. Purchasing faster speed ram will do nothing for you in any way. It will not run any faster than the bus speed of the system which is 667 Mhz. Why waste the $$$?
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needlewithaprun

 
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Quote:
Originally Posted by iNick View Post
Id go for the cheaper of the two cause you won't notice the difference.
Is there really no difference between the two?
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iNick

 
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You asked if there is any difference real world performance wise, I say that there isn't. Perhaps if you were buying a maxed out Mac pro for controlling a rocket ship on NASA's next space mission, then I'd go for the faster RAM. If I had to quantise the performance increase, Id say (and by no means is this based on anything other then personal experience) if you were encoding a CD in iTunes it might, if at all, finish 1/3 of a second quicker with the faster RAM.

Besides if you mix 667 with 800, as per my last post, the speed of the 800 becomes effectively 667. Ask an expert (not the person trying to sell it to you) and they will say the same thing. So unless you replace both RAM modules you will not get the speed boost.

Keep in mind that Apple themselves couldn't see the benefit.
I wouldn't waste my money.
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bobtomay

 
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technologist is correct (still have to spread it around tech)

according to Apple's tech specs, the bus speed is 800Mhz only between the CPU and the northbridge, the bus speed between the northbridge and the memory is 667Mhz.

Putting a memory chip with a speed higher than the bus speed in a machine with EFI and basically no tweaking capability on the motherboard to overclock (at least not easily) is wasted money. You will see no performance gain with them based on the clock speed. If you can find some 800 with lower latency than any 667 (unlikely) you may see a very small performance gain, but would not likely be enough to notice without running speed tests between the two of them.

edit: have to say I do not know enough about EFI boards to even know how or even if these boards make adjustments between different latency memory.

I cannot be held responsible for the things that come out of my mouth.
In the Windows world, most everything folks don't understand is called a virus.
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