'mid 2010' 27" iMacs Compared:
Core i3 vs Core i5 vs Core i7
Posted Friday, August 6th, 2010, by rob-ART morgan, mad scientist
Wed, August 11th, 2010, corrected X-Plane results
and added After Effects CS5 results
DO I REALLY NEED A CORE i7?
I get that a lot. The top 'mid 2010' iMac is the 27" Core i7 2.93GHz at $2199. The 27" Core i5 2.8GHz is $1999 ($200 less). The 27" Core i3 3.2GHz is $1699 ($500 less than the Core i7).
We would love to have one of everything in our lab but until we can afford that or borrow time on one of each, we have enlisted the help of "remote mad scientists," otherwise known as "readers." We don't have all the results we hope to post but here's a taste for those who can't wait.
In the first two graphs, LONGER bar means FASTER.
IS THE TOP iMAC THE BEST BUY?
The 'mid 2010' iMac Core i7, is as much as 45% faster than the Core i5 for 10% more cost.
The Core i7 is as much as 104% faster (twice as fast) as the Core i3 for 29% more cost.
The Core i5 is as much as 41% faster than the Core i3 for 18% more cost.
To put it another way, going by the Cinebench rating,
you pay $400 for each rating point on the Core i7,
you pay $526 for each rating point on the Core i5, and
you pay $629 for each rating point on the Core i3.
Want real world? In the After Effects render test,
the Core i7 beats the Core i5 by 33%, though costing 10% more, and,
the Core i7 beats the Core i3 by 42% though costing 29% more.
Want more real world? In the iMovie "export to HD" test,
the Core i7 beats the Core i5 by 20% though costing 10% more, and,
the Core i7 beats the Core i3 by 34% though costing 29% more.
I say the top iMac model is the best buy.
1. Be aware that hyper-threading or turbo boost are not features available in all models.
2. I tested our Core i7 with 4GB of RAM because that's the amount the "remote mad scientists" had in their Core i5 and Core i3. I recommend more memory if you are running apps like Photoshop, Motion, and After Effects. For example, After Effects limits the number of real (and virtual) cores it uses if you can't dedicate at least .75G to each one. It runs fastest if you dedicate at least 1GB to each core.
THREE MORE ARGUMENTS
1. The "light use" argument:"I only use my iMac to read email and surf the net. Why do I need multiple cores with hyper-threading and a fast graphics card?"
2. The "future proofing" argument: As the OS and apps get more sophisticated and demanding, the top model will be useful longer.
3. The "resale" argument: When you sell it on Craigslist or eBay, the top model will bring in more money -- possibly enough to recover the cost difference when new.
Hopefully I've muddied the waters sufficiently. HAVE AN OPINION? Feel free to email me,
, mad scientist.
Thanks to Mongo Mike and B.H. for contributing the Core i5 results. Thanks to E.A. for contributing the Core i3 results.
One issue that buyers face is whether to get the iMac with 21" screen or 27" screen. The iMacs with the 21" screen are limited to using the Radeon HD 5670 while the iMacs with 27" screens can opt for the Radeon HD 5750. What are you giving up by settling for the Radeon HD 5680? Check out the graph below where I "dumbed down" the 27" iMacs to run at the same 1920x1080 resolution of the 21" iMac. (I'll add the Core i5 iMacs to this graph soon.)
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