New iMac - Memory speed

Joined
Jul 23, 2007
Messages
10
Reaction score
0
Points
1
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
 
Joined
Jun 16, 2007
Messages
424
Reaction score
8
Points
18
Location
Belgium, Brussels
Your Mac's Specs
MacBook Pro
Get the 800, it's much faster.
 
Joined
Mar 30, 2004
Messages
4,744
Reaction score
381
Points
83
Location
USA
Your Mac's Specs
12" Apple PowerBook G4 (1.5GHz)
Get the 667. The 800MHz memory won't run any faster at all in an iMac.
 
Joined
Aug 10, 2007
Messages
5
Reaction score
0
Points
1
Get the 667. The 800MHz memory won't run any faster at all in an iMac.

I beg to differ:

* 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/listparts.aspx?model=iMac 2.0GHz Intel Core 2 Duo (20-inch) MA876LL

So if it was no faster, then why would they do so?.
 
Joined
Mar 30, 2004
Messages
4,744
Reaction score
381
Points
83
Location
USA
Your Mac's Specs
12" Apple PowerBook G4 (1.5GHz)
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/document...le_ref/doc/uid/TP40003899-DontLinkElementID_7
The SO-DIMMs must be DDR2-667 (PC2-5300) compliant

Note also the block diagram here:
http://developer.apple.com/document...html#//apple_ref/doc/uid/TP90004829-TPXREF101
Which clearly notes that the RAM slots run at 667MHz

Shall I PM you with my address for my £100?
 
Joined
Jul 2, 2007
Messages
27
Reaction score
0
Points
1
Location
California
Your Mac's Specs
24' Al_iMac 2.8GHz 4GB Ram 1TB HD, 15" PB 1.5GHz 1GB Ram 160GB HD, 2x30GB iPod, 2x Shuffle, Nano
Huh?

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?
 
Joined
Dec 18, 2005
Messages
2,288
Reaction score
51
Points
48
Location
Devon, England
Your Mac's Specs
ibook g4, imac 2ghz c2d, mbp 2.4ghz c2d - 10.5.1
I fixed your post.

lol. i dont know the difference. but i would assume there isnt much difference between the two speeds.
 
Joined
Aug 2, 2007
Messages
38
Reaction score
0
Points
6
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.
 

dtravis7


Retired Staff
Joined
Jan 4, 2005
Messages
30,133
Reaction score
703
Points
113
Location
Modesto, Ca.
Your Mac's Specs
MacMini M-1 MacOS Monterey, iMac 2010 27"Quad I7 , MBPLate2011, iPad Pro10.5", iPhoneSE
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 $$$?
 
Joined
Aug 2, 2007
Messages
38
Reaction score
0
Points
6
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.
 

bobtomay

,
Retired Staff
Joined
Dec 22, 2006
Messages
26,561
Reaction score
677
Points
113
Location
Texas, where else?
Your Mac's Specs
15" MBP '06 2.33 C2D 4GB 10.7; 13" MBA '14 1.8 i7 8GB 10.11; 21" iMac '13 2.9 i5 8GB 10.11; 6S
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.
 

Shop Amazon


Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
Top