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Old Nov 29, 2012, 01:47 PM   #1
js09
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Turbo Boost 3.6GHz for both 27" models - why pay more?

if both the $1800 and $2000 imacs both run at 3.6Ghz, why pay for the more expensive one?
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Old Nov 29, 2012, 01:51 PM   #2
joe-h2o
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Originally Posted by js09 View Post
if both the $1800 and $2000 imacs both run at 3.6Ghz, why pay for the more expensive one?
The more expensive one has a *much much much* better GPU.

The better CPU is just a bonus at that point.
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Old Nov 29, 2012, 03:32 PM   #3
js09
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The more expensive one has a *much much much* better GPU.

The better CPU is just a bonus at that point.
meh.. neither have a good GPU so i don't care much about that.. I just want to know how the CPU works. are both CPU's identical after enabling turbo boost?

----------

I wouldnt be surprised if both 27" models have the exact same CPU (ie.. intel 2500k). where can i find out?
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Old Nov 29, 2012, 03:33 PM   #4
njooste
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Actually, the 680mx is quite a beast
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Old Nov 29, 2012, 03:43 PM   #5
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The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare.

btw the two processors are most likely i5-3470 and i5-3470S.

Last edited by lixuelai; Nov 29, 2012 at 03:49 PM.
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Old Nov 29, 2012, 03:46 PM   #6
vladfein
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Quote:
Originally Posted by lixuelai View Post
The 3.6Ghz Turbo Boost only kicks in if you are utilizing only 1 core which is fairly rare.
Where is this info from?
Sure not from http://www.apple.com/imac/performance/ ...
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Old Nov 29, 2012, 03:48 PM   #7
js09
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Quote:
Originally Posted by njooste View Post
Actually, the 680mx is quite a beast
no, not really. it depends on what it's used for

anyway, just guessing 2 of these processors are the ones used:


i5-3470S (2.9GHz)
i5-3470 (3.2GHz)

----------

Quote:
Originally Posted by vladfein View Post
Where is this info from?
Sure not from http://www.apple.com/imac/performance/ ...
Quote:
Originally Posted by lixuelai View Post
The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare.
If I had to guess, the turbo boost only kicks in when utilizing all 4 cores to their max. it just idle's at the base speed. kicking in upon 1 core sounds retarded.. but maybe

edit: just read the link above. looks like i'm probably right
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Old Nov 29, 2012, 03:57 PM   #8
lixuelai
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Originally Posted by vladfein View Post
Where is this info from?
Sure not from http://www.apple.com/imac/performance/ ...
To quote Intel:

Quote:
Max Turbo Frequency refers to the maximum single-core frequency that can be achieved with Intel® Turbo Boost Technology, which requires a PC with a processor with Intel Turbo Boost Technology capability. Intel Turbo Boost Technology performance varies depending on hardware, software, and overall system configuration. Check with your PC manufacturer on whether your system delivers Intel Turbo Boost Technology. See www.intel.com/technology/turboboost/ for more information.
The max is always single core.
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Old Nov 29, 2012, 04:02 PM   #9
joe-h2o
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Quote:
Originally Posted by js09 View Post
no, not really. it depends on what it's used for

anyway, just guessing 2 of these processors are the ones used:


i5-3470S (2.9GHz)
i5-3470 (3.2GHz)

----------





If I had to guess, the turbo boost only kicks in when utilizing all 4 cores to their max. it just idle's at the base speed. kicking in upon 1 core sounds retarded.. but maybe

edit: just read the link above. looks like i'm probably right


I'm not sure what plane of reality you're from where you think the 680MX is "not really" a good GPU, but can I visit? It sounds weird and wonderful there!
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Old Nov 29, 2012, 04:05 PM   #10
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Quote:
Originally Posted by js09 View Post
meh.. neither have a good GPU so i don't care much about that.. I just want to know how the CPU works. are both CPU's identical after enabling turbo boost?

----------

I wouldnt be surprised if both 27" models have the exact same CPU (ie.. intel 2500k). where can i find out?
The 680mx is as fast as an underclocked desktop 680mx(and Apple likely overclocked it like on their MBPs so it's probably on par) .

Is it fun not knowing what you're talking about?
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Old Nov 29, 2012, 04:06 PM   #11
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Quote:
Originally Posted by js09 View Post
If I had to guess, the turbo boost only kicks in when utilizing all 4 cores to their max. it just idle's at the base speed. kicking in upon 1 core sounds retarded.. but maybe
Totally wrong. Current processors are limited by the heat they produce. More MHz = more heat. More cores running = more heat. Running fast for long time = more heat.

An Intel processor sold as "2.9 GHz" can run at 2.9 GHz with all cores running 24/7. If only one core is running, and the computer has been idle and is therefore quite cool, only then can it run at the higher "Turbo" speed. So if you need a computer running at full speed all the time, look at the lowest quoted speed.
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Old Nov 29, 2012, 04:10 PM   #12
js09
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I use a quadro so I should rephrase and say the GPU is not suitable for my needs. it does look like a worthwhile upgrade, though.
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Old Nov 29, 2012, 04:11 PM   #13
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Quote:
Originally Posted by js09 View Post
meh.. neither have a good GPU so i don't care much about that.. I just want to know how the CPU works. are both CPU's identical after enabling turbo boost?

I wouldnt be surprised if both 27" models have the exact same CPU (ie.. intel 2500k). where can i find out?
Maybe not for you but there is a huge difference between the 660m and the 675mx/680mx. I'd say that for casual gaming the 675mx is needed at a minimum. Considering Apple only wants to make things even thinner this is as good as we're going to see in such a small form factor. The 660m is similar to the 6750m in my 17" MBP, which is "meh".


You can check out everymac.com for exact CPU model numbers shipping with the new iMacs.
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Old Nov 29, 2012, 04:14 PM   #14
js09
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Originally Posted by gnasher729 View Post
Totally wrong. Current processors are limited by the heat they produce. More MHz = more heat. More cores running = more heat. Running fast for long time = more heat.

An Intel processor sold as "2.9 GHz" can run at 2.9 GHz with all cores running 24/7. If only one core is running, and the computer has been idle and is therefore quite cool, only then can it run at the higher "Turbo" speed. So if you need a computer running at full speed all the time, look at the lowest quoted speed.
interesting.

my i7 2600k runs @ 5.0Ghz overclocked, but i *think* idle's at around 2 or 3 Ghz when "not in use". I was thinking along the same terms here, but I see what you're saying.. I wonder how it will perform. I would think that it can indeed run all 4 cores on turbo boost when needed but i guess not

----------

Quote:
Originally Posted by ihuman:D View Post
The 680mx is as fast as an underclocked desktop 680mx(and Apple likely overclocked it like on their MBPs so it's probably on par) .

Is it fun not knowing what you're talking about?
see my post above.
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Old Nov 29, 2012, 04:19 PM   #15
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Originally Posted by js09 View Post
interesting.

my i7 2600k runs @ 5.0Ghz overclocked, but i *think* idle's at around 2 or 3 Ghz when "not in use". I was thinking along the same terms here, but I see what you're saying.. I wonder how it will perform. I would think that it can indeed run all 4 cores on turbo boost when needed but i guess not

----------



see my post above.
Oops ! Sorry!

The 680mx would be better for gaming and general usage while the Quadro would be better for Pros(Well that's how it used to be with the Quadros) .
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Old Nov 29, 2012, 04:22 PM   #16
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Quote:
Originally Posted by lixuelai View Post
To quote Intel:

The max is always single core.
That might be, but I was questioning your:
"The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare."
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Old Nov 29, 2012, 04:25 PM   #17
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Originally Posted by vladfein View Post
That might be, but I was questioning your:
"The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare."
How so? 3.6Ghz is the Max Turbo Boost frequency listed by Intel. I already quoted the Max Turbo Boost definition.

Btw even the Apple specs page lists "up to" which is the same way Intel describes the Max.
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Old Nov 29, 2012, 04:43 PM   #18
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Originally Posted by lixuelai View Post
How so? 3.6Ghz is the Max Turbo Boost frequency listed by Intel. I already quoted the Max Turbo Boost definition.

Btw even the Apple specs page lists "up to" which is the same way Intel describes the Max.
You stated above:
"The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare."
Correct me if I am wrong, but I understood your statement as requirements for three of four cores to be idle (or near idle).
Or what exactly did you mean by "if you are only utilizing 1 core"???
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Old Nov 29, 2012, 04:51 PM   #19
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Originally Posted by vladfein View Post
You stated above:
"The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare."
Correct me if I am wrong, but I understood your statement as requirements for three of four cores to be idle (or near idle).
Or what exactly did you mean by "if you are only utilizing 1 core"???
That's correct, the max turbo boost is only when using 1 core, ie all other 3 idle.
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Old Nov 29, 2012, 04:54 PM   #20
lixuelai
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Quote:
Originally Posted by vladfein View Post
You stated above:
"The 3.6Ghz Turbo Boost only kicks in if you are only utilizing 1 core which is fairly rare."
Correct me if I am wrong, but I understood your statement as requirements for three of four cores to be idle (or near idle).
Or what exactly did you mean by "if you are only utilizing 1 core"???
That is precisely what I meant. The 3.6GHz will only happen when 1 core is stressed. When 2 cores are stressed the cores may run at 3.4Ghz (an example, I don't know the exact number) and so on but 3.6GHz which is listed as the max is always single core.

Anyway you can try it yourself actually, Turbo Boost is present on nearly every Intel processor since Nehalem. Easiest way is to run something like SuperPi and watch the clockspeeds.

Last edited by lixuelai; Nov 29, 2012 at 05:00 PM.
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Old Nov 29, 2012, 05:00 PM   #21
vladfein
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Originally Posted by lixuelai View Post
That is precisely what I meant. The 3.6GHz will only happen when 1 core is stressed. ...
Got it. I thought that you said that NO Turbo Boost will get kicked on multiple cores at all.
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Old Nov 29, 2012, 05:11 PM   #22
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Originally Posted by js09 View Post
I use a quadro so I should rephrase and say the GPU is not suitable for my needs. it does look like a worthwhile upgrade, though.
I heard that a lot of the current gaming cards are out performing the quadro for professional tasks these days. Therefore the 680mx might just do that too haha. The CUDA cores for GPU rendering in gaming cards seem to be the culprit for that I think.
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Old Nov 29, 2012, 05:23 PM   #23
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Originally Posted by vladfein View Post
Got it. I thought that you said that NO Turbo Boost will get kicked on multiple cores at all.
When all physical and virtual cores are used at 100% each then there will be no turbo boost. It will be running at whatever speed the CPU is, 2.9, 3.2GHz, whatever.
Turbo boost speeds up certain things, by shutting down cores and the electricity that now no longer flows to the idle cores goes to the other cores and those remaining active cores will be boosted. The highest turbo number stated anywhere will be for ONE core only. The numbers drop slightly for when two cores are boosted, three, four etc.
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