1333mhz ram working and registering in my 1066mhz original imac

Qwerty11

macrumors regular
Original poster
Sep 1, 2010
207
2
I thought 1333 mhz ram would under clock to 1066mhz in my late 09 iMac. However, on the system hardware screen it is showing up as 1333 mhz ram. What gives?
 
Last edited:

visim91

macrumors 6502
Nov 13, 2011
332
0
So it's working, right?
If so, I would just go ahead and exit that system hardware screen and spend more time enjoying your new & improved memory. ;)
 

Qwerty11

macrumors regular
Original poster
Sep 1, 2010
207
2
Yea its working. I'm just perplexed because everybody told me it would register as 1066mhz. Strange.
 

SandboxGeneral

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Sep 8, 2010
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Wirelessly posted (iPhone 4S: Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3)

Are you certain that the logic board is 1066 and not really 1333?
 

szolr

macrumors 6502
Jul 27, 2011
376
0
London, UK
RAM always runs at the slowest present speed I believe. So if all the RAM chips are upgraded to 1333MHz and you take out the 1066MHz bits everything will run at 1333MHz. But if you mix and match they SHOULD all run at 1066MHz. I think?
 

Qwerty11

macrumors regular
Original poster
Sep 1, 2010
207
2
See the thing is though everything I read on hear said I could use 1333, but it would only run and register at 1066 because that is what the logic board was setup for.
 

nicroma

macrumors 6502a
Jun 20, 2009
504
30
Midwest, USA
No, 1333 can be detected, but there have been CAS latency issues with some people, so make sure you are using 1333 chips with the correct timings. Your safest bet is 1066 chips.
 

mpe

macrumors 6502
Sep 3, 2010
314
189
As of Intel Core CPUs the memory controller is integrated in CPU. That's why the chipset or logic board has nothing to do with memory speed/compatibility.

All intel CPU's support 1333 MHz memories.

I run 1333 MHz memories in my late2009 iMac too.
 

tnewson

macrumors member
Nov 15, 2011
30
1
London
Does this mean that a faster clock speed ram would work in my 2011 imac?

Currently has 1333mhz ram.. will it support say, 1600mhz or even 1866mhz ram? Assuming i remove the lower clock speed ram before,
 

theSeb

macrumors 604
Aug 10, 2010
6,963
91
Poole, England
Does this mean that a faster clock speed ram would work in my 2011 imac?

Currently has 1333mhz ram.. will it support say, 1600mhz or even 1866mhz ram? Assuming i remove the lower clock speed ram before,
Yes. People are running 1600 memory in their 2011 minis. It gives about an extra 5% in geek bench.
 

tnewson

macrumors member
Nov 15, 2011
30
1
London
Yes. People are running 1600 memory in their 2011 minis. It gives about an extra 5% in geek bench.
**** the bed! Well gutted, I just bout another 8gb of 1333... Double gutted because I've just found out i can upgrade to 32gb instead of 16gb :(
 

mpe

macrumors 6502
Sep 3, 2010
314
189
So can I theoretically run 1866mhz in my original 1066mhz system?
No. Original i5-750 or i7-860 from late 2009 and 2010 iMacs only support 1066 and 1333 MHz.

Even CPUs from 2011 iMacs (i5-2400/s i5-2500/s i7-2600/s) does not support 1866 MHz memories.

You might install them, they will run at 1333, but the performance could be actually lower as result of higher latencies.
 

aliensporebomb

macrumors 68000
Jun 19, 2005
1,844
223
Minneapolis, MN, USA, Urth
1333 memory on 2009 iMac 2009 i7 model

The motherboards on these systems were convertible supporting either type of memory. I replaced all of my ram in my i7 iMac and it runs at 1333 speed and benches faster too and some operations feel a little faster.

I believe Apple shipped these systems with 1066 memory because it was less expensive for them to source at the time and they also could release a later model touting this as a feature.

 

ArcspacE

macrumors member
Jul 31, 2009
56
0
Put in 1333 4GB sticks in my early 2009 3.06GHz iMac and it works just fine.

Could it damage the logic board long term?
 
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