2.9GHz i5 or 3.1GHz i7 ?

Discussion in 'iMac' started by lisa360, Feb 1, 2013.

  1. lisa360 macrumors newbie

    Jan 13, 2009
    I am getting ready to order tonight! 21.5'' iMac with the Fusion Drive and 16GB RAM. Since I am spending so much already I thought about upgrading to the 3.1GHz. Is the speed/difference really that noticeable? This will be my first iMac and I will be coming from a 2.26GHz Intel Core 2 Duo Macbook Pro so either one will be an improvement.
  2. USAntigoon macrumors regular


    Feb 13, 2008
    Rochester Hills, MI
  3. Aqueous macrumors member

    Jun 10, 2004
    Haha, came from the same exact computer! I got the 27" 3.4 i7 and it absolutely screams. I have no idea what you use your computer for, so it is almost impossible to answer your question. But I can tell you coming from a bench score of 2800 to 12800 is "noticeable"... You 're going to be stoked no matter what. If you push your machine (PS, LR, etc...) than get the i7 for its threading. Once I export photos or build a gallery or whatever, its like a turbine or turbo klicks in and what used to take me 45 minutes is done in like 2 minutes, no BS!! It astounds me.
  4. brand macrumors 601


    Oct 3, 2006
    Yes for some, no for others.
  5. lisa360 thread starter macrumors newbie

    Jan 13, 2009

    Oops, should have done a search first! Thanks so much for the link. :)


    I will be using it for general Internet and Adobe CS6 (Photoshop, InDesign, Illustrator...a bit of Dreamweaver). No real video editing, and no gaming.

    The 27'' is so gorgeous...I just came back from the Apple store and I was blown away at the size of the screen. I think the 27'' will be my choice in a few years. I can't wait to finally order and receive mine now! :)
  6. mrjose macrumors newbie

    Sep 25, 2012
    I have the 3.1 GHz i7 with Fusion Drive and 16GB RAM. My wife generally uses CS6 apps like Photoshop and Premiere Pro along with Chrome, Safari, etc. In the first few weeks, I have been checking activity monitor off and on. Based on this, I would rank the 21.5 "options" in order of most important to least important:

    1. Fusion drive provides definite improvements in performance, opening files, etc. Having a slow hard drive would be noticeable for sure.

    2. Looking at the system monitor, I've been over 8GB of RAM a few times. But, most times, there is less than 8GB used, even with 6-10 apps running at once. If I only had 8GB, the iMac would swap to the fusion drive with minimal loss of performance. So, that's why I feel that the Fusion drive is more important than the extra RAM.

    3. I rarely see on Activity Monitor that the processor uses much more than 25% of its capacity, no matter what I do. So, I'm interpreting that I have much more capacity than I need today. Doing SD video on Premiere Pro is super fast. And, I tried to make the processor "work" by doing different Photoshop effects. Every digital effect that I tried was pretty much instantaneous.

    So, thus far, I'm not seeing situations where the processor appears to limit performance. I expect, for what we do, we have more machine than needed. (Of course, if I had a slower machine, it's possible that I'd have a different opinion.) Down the road, I plan to do HD video editing, which I know will be much more challenging.

    So, if you want to have no worries that you bought too slow of a machine, spend the money for the upgrade. But, if you're doing stuff like I described above, the i5 processor may be just fine.
  7. WizardHunt macrumors 68000


    May 11, 2007
    Las Vegas, Nevada USA
    pick the 3.1 over 2.9 Ghz anyway. I am always about power and speed.
  8. Mike in Kansas macrumors 6502a

    Mike in Kansas

    Sep 2, 2008
    Metro Kansas City
    How about rendering a Premiere Pro project to a finished video file, like H.264 format? Or a handbrake encoding? Both of those should really tax the processor and give you a good idea of performance.
  9. mrjose macrumors newbie

    Sep 25, 2012
    Using Premiere Pro, I imported 2.5 minutes of SD video (720x480) and then ran Export->Media using these settings: Format: H.264, Preset: HD 1080p 29.97. This took a bit over 3 minutes on my system (3.1 GHz i7, 16 GB RAM, Fusion Drive). Per the activity monitor, the CPU was about 80-85% in use (%User+%System).

    So, this test definitely showed where the i7 makes a difference. My original point was that in my most common uses the CPU is way more than I need. The i7 CPU makes certain functions faster, but you pay for it up front, whether you use it or not.

    I guess the decision is comparable to buying a bigger engine in a car to make acceleration faster. But, if I spend all my time driving on the highway, it wouldn't be as attractive an option.

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