iMac i5/7 Frontside bus/Memory question: 1066 or 1333?

onedamngoal

macrumors member
Original poster
Apr 9, 2009
32
0
http://support.apple.com/kb/SP576

Scroll down to Configurations. The Frontside bus for the Core 2 Duo 21.5-inch and 27-inch lists the Frontside bus as 1066Mhz. The Frontside Bus for the the Core i5 is listed as - .

The Memory for Lynnfield chips; which the new iMac Quad-Core uses is 1333mhz.

http://en.wikipedia.org/wiki/List_of_Intel_Core_i7_microprocessors#.22Lynnfield.22_.2845_nm.29

Will buying these http://www.newegg.com/Product/Product.aspx?Item=N82E16820231295 over these http://www.newegg.com/Product/Product.aspx?Item=N82E16820231294
create less of a bottleneck?

P.S. Is anyone thinking about putting in a WD Velociraptor in there new iMacs?
 

rrijkers

macrumors 6502
Jun 6, 2007
294
1
The Netherlands
There is no FSB on the i5 or i7.

The memory spec from Apple says you need the 1066 (PC8500).
Yeah, I start to believe it fits 1333 memory too. We need to have this confimed by the time they are put to market. Apple more often than not tends to lower certain specs and stuff even when it is not true.
 
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TMRaven

macrumors 68020
Nov 5, 2009
2,099
1
The voltage/number of pins are the same, and the lynnfields do support up to 1333 mhz ram speeds. Apple's also been wrong before on their ram configurations-- people have found configurations that apple had yet to publicly display on their site as official configurations in the past. Just as likely you can upgrade your ATA drive in the iMac for an SSD, but it's not officially recognized by apple.

I really would like to think the new iMacs are capable of that small boost in ram speed, but we won't know for sure until someone gets a lynnfield iMac and attempts to put 1333mhz ram in it.
 
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OddHead

macrumors member
Jun 11, 2009
41
0
Intel says on this page:

Memory Types DDR3-1066/1333

It's not the first time Apple puts lower memories in their products, it happened also some time ago with pre-unibody MBPs. I don't know why, but reading on Intel website of an "official" 1066 Mhz DDR3 RAM support makes me less doubtful about performance loss.

I'm also waiting some tests on 1333 Mhz compatibility once i7 (and i5) based iMacs start shipping.

edit: i forgot: maybe 1333 SO-DIMMs modules (the ones used by Apple everywhere except MP) are now less available, or simply more expensive than 1066 ones.
 
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rrijkers

macrumors 6502
Jun 6, 2007
294
1
The Netherlands
edit: i forgot: maybe 1333 SO-DIMMs modules (the ones used by Apple everywhere except MP) are now less available, or simply more expensive than 1066 ones.
This is certainly the case and most of the time the reason why apple advises against it.

Basicly all we need it proof :) Stick in another 2x2 1066 for now and wait for 1333 memory prices to drop in a year (and a half) time
 
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morficus

macrumors member
Oct 26, 2009
72
0
North East, USA
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filmgirl

macrumors regular
May 16, 2007
215
8
Seattle, WA
I almost ordered some 1333 to test with my new iMac, because it absolutely should clock itself down -- but I held back for two reasons:

1) When I ordered my RAM last week, $80 was the best with shipping price I could get on 1066 stuff (this was Crucial), that's $35 more than what I spent on the EXACT SAME RAM (same SKU and everything) in like June or July when I got stuff for my mid-2009 iMac (that I ordered in early June). The 1333 stuff was yet another $20 or $25 premium.

2) Without seeing the 1333 stuff tested in the new Macs, we won't know what RAM is considered reliable or not. If you'll recall, people with the 1066 DDR3 stuff had some issues in the beginning with RAM (even the stuff deemed "Apple Spec" because some of the timings were off and the stuff just didn't play nice in the Macs. It's totally not worth the theoretical increase (because it is theoretical now unless I'm willing to replace all the RAM with 1333 stuff), for me to play guinea pig until we get some more test cases and get a solid answer.

3) To take full advantage I'd have to replace all of the RAM with 1333 stuff. So that's another $200 - $250 total to spend, for what I don't think will noticeable. What I'd rather do is wait a year and go for say, 4 4GB 1333 sticks or 2 4GB sticks or something rather than replacing all of it now, when I'm still going to have to replace all of it in the future if I want 16 GB.

But yeah, we'll have to wait and see what people do. I feel confident that the right RAM will run because as far as I know, Apple doesn't do anything to modify the memory slots on those boards -- they are custom boards, but Apple doesn't modify that stuff.
 
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rrijkers

macrumors 6502
Jun 6, 2007
294
1
The Netherlands
3) To take full advantage I'd have to replace all of the RAM with 1333 stuff. So that's another $200 - $250 total to spend, for what I don't think will noticeable. What I'd rather do is wait a year and go for say, 4 4GB 1333 sticks or 2 4GB sticks or something rather than replacing all of it now, when I'm still going to have to replace all of it in the future if I want 16 GB.
You might also order those two 1333 ones. Put them in there see if it works, put the other ones in there if you are ready and swap them out when you want to replace them all :)

ps. tuaw filmgirl?
 
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filmgirl

macrumors regular
May 16, 2007
215
8
Seattle, WA
You might also order those two 1333 ones. Put them in there see if it works, put the other ones in there if you are ready and swap them out when you want to replace them all :)

ps. tuaw filmgirl?
Not a bad idea -- but I figure I'll wait for the price to go down. Already RAM is dropping from even two weeks ago. It's all based on Asia so once we see prices get lower I'll re-evaluate.

And yes -- TUAW filmgirl -- currently Mashable filmgirl, and Twitter @film_girl. :)
 
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yargok

macrumors newbie
Jun 18, 2009
22
1
You might also order those two 1333 ones. Put them in there see if it works, put the other ones in there if you are ready and swap them out when you want to replace them all :)
I was thinking about doing the same thing:

  1. Buy imac (i7) with stock 4gig of ram (1066)
  2. Now, buy 2x2gb 1333 ram to bump the system to 8 gig. System still operates at 1066
  3. In the future, when 4 gigs are cheap, buy 2x4gb 1333 ram. System now operates at 1333

I just want verification that 1333 ram is compatible (hopefully with a specific model) and make sure that it downclocks ram is mixed, and upclocks when only fast ram is present.
 
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zaphoyd

macrumors regular
Jun 25, 2002
121
31
Wisconsin/Illinois
I was thinking about doing the same thing:

  1. Buy imac (i7) with stock 4gig of ram (1066)
  2. Now, buy 2x2gb 1333 ram to bump the system to 8 gig. System still operates at 1066
  3. In the future, when 4 gigs are cheap, buy 2x4gb 1333 ram. System now operates at 1333

I just want verification that 1333 ram is compatible (hopefully with a specific model) and make sure that it downclocks ram is mixed, and upclocks when only fast ram is present.
This was my thought as well. A coworker got some new RAM for his C2D iMac and it was the same speed but a different CAS latency (original ram was CAS5, new was CAS6) it didn't work. He had to send it back and get a CAS5 version. Granted he has the system set up with a custom EFI that lets him triple boot Linux/Windows/OS X.....

It would just be nice if there was a repair shop or something that could pop a few in just to see what happens.

I am really tempted to just buy some 1333 stuff since it is like +/-$5 these days but I am not sure if it is worth the hassle of having to return it if it doesn't work. Does anyone think it would be a problem to return a pair of chips and get a slower speed without getting charged restock fees or something from newegg or whereever?
 
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rrijkers

macrumors 6502
Jun 6, 2007
294
1
The Netherlands
And yes -- TUAW filmgirl -- currently Mashable filmgirl, and Twitter @film_girl. :)
I am following you on Twitter for some time now :)

It would just be nice if there was a repair shop or something that could pop a few in just to see what happens.
I am sure your local shop will do that if you guarantee them you buy the chip if it works :) I get my i7 the 10th of Dec so I have some waiting to do :)
 
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DoFoT9

macrumors P6
Jun 11, 2007
17,512
33
Singapore
Fingers crossed that the memory can go at the higher rate!
i hope so too! but preliminary tests from other users shows that its locked at 1066MHz (via EFI). i sure hope that they are wrong.

This person here put in 1600Mhz Memory?

http://browse.geekbench.ca/geekbench2/view/185342

The result stands out a little from the rest of the results in the chart. The Ghz's seem a little off too
thats a hack. the iMac's have a Core i7 860 cpu not 870.
damn, beat me too it :rolleyes:
 
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fruitpunch.ben

macrumors 6502a
Sep 16, 2008
588
160
Surrey, BC
i hope so too! but preliminary tests from other users shows that its locked at 1066MHz (via EFI). i sure hope that they are wrong.
me too!
but i'm not looking at doing it any time soon, by the time I'm ready to buy more ram we should have a definative answer!
I should be fine with 4GB RAM for the next 12 months, then hopefully 4x4GB chips will be $100-150 next christmas, and I shall stick them in then :)

damn, beat me too it :rolleyes:
:p
 
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DoFoT9

macrumors P6
Jun 11, 2007
17,512
33
Singapore
me too!
but i'm not looking at doing it any time soon, by the time I'm ready to buy more ram we should have a definative answer!
I should be fine with 4GB RAM for the next 12 months, then hopefully 4x4GB chips will be $100-150 next christmas, and I shall stick them in then :)
yeah ill leave it at 4GB for a while. if my swap file etc are getting too large then i will upgrade to 8GB, which should do me for a year or so. :) :cool:
 
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OddHead

macrumors member
Jun 11, 2009
41
0
Uhm... i7's frequency is 2.8 GHz, not 2.84, and "FSB" (which is not FSB anymore, but DMI) should be 4.8 GHz, or GT/sec, but not 532 MHz... there's some mistake.
 
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