Considering i5 to i7 upgrade for VT-d and HT?

Discussion in 'iMac' started by Woutje, Aug 15, 2010.

  1. Woutje macrumors member

    Aug 21, 2005
    Hi all,

    I'm considering the new iMac, fastest model, but first comparing the i7 upgrade to stock i5, and determining if it is worth another 180 euro.

    After researching I've come to the conclusion that there's only a few minor differences:
    - Faster clock speeds: 2.8 vs 2.93 (minor)
    - Hyperthreading support for i7
    - VT-d and TXT virtualisation support for i7

    In reality there's not much difference. I've found a comparison on Anandtech.

    Do note that the i5 model is actually a slower one, as the i5-760 wasn't in the chart. Instead I went with the 750, so the i5-i7 difference should be even smaller.

    As I do like to run Parallels Desktop (mostly to test websites cross-browser), I'm mostly interested to hear if the VT-d and TXT support actually makes a difference. To me, the faster clock speed and HT don't really seam all that important.

    If you already have 4 cores, does it help to have 8 (of which 4 virtual) ? Tell me if I'm wrong here.
  2. CWallace macrumors 603


    Aug 17, 2007
    Seattle, WA
    Depends on whether or not your application works across multiple cores and threads and if it does, how well it scales.

    I have the 2.8GHz i7 from the last generation iMac and in applications like Handbrake that support multiple cores/threads and scales fairly decently across them, it has resulted in a serious performance boost.
  3. Vylen macrumors 65816

    Jun 3, 2010
    Sydney, Australia
    Nope.. if all you're doing is running browsers...
  4. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    If you really want some bang to your buck, get the 2.8GHz i7 from refurb store
  5. aliensporebomb macrumors 68000


    Jun 19, 2005
    Minneapolis, MN, USA, Urth
    It helps me. I'm running corei7 2.8 ghz and there's a number of apps that make this machine function like an OctoCore:

    -Logic (I can run more software synthesizers or effects plug-in or tracks simultaneously, a big deal for me)
    -iStat Menus (evidence the extra "cores" are helping you out)
    -BOINC / Seti @ Home (I can run eight workunits at once instead of four)
    -Handbrake (runs much faster - 200fps from a mounted disc image)

    -Even parts of iLife use hyperthreading to some degree (GarageBand, iPhoto, iMovie)

    I determined that anecdotally just by watching the processor meters in one window while doing high-processor functions in those apps.

    (Notably, Logic Express 7 doesn't use hyperthreading at all).

    Mind you, as time goes by more and more apps will use hyperthreading and extra cores so it's win-win IMO.

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