3.4Ghz, 3.5Ghz or 3.8Ghz

Discussion in 'iMac' started by xzebra, Feb 26, 2018.

  1. xzebra macrumors newbie

    Feb 20, 2018
    Thanks to all of your help so far this site has got me pursue my first iMac purchase. So I want to make sure I am getting the best bang for the buck, looking at new and refurb.

    I cannot afford much more than $2100-2300 after taxes and if refurb iCare. Wanting assistance on the three main processors and if there is a great bit of difference in them - 3.4Ghz, 3.5Ghz or 3.8Ghz.
    My worry is processors and tech changes so fast I want to be the most current without draining the bank.

  2. jerwin macrumors 68020

    Jun 13, 2015
    The CPUs aren't the differenting feature, so much as the things that come with each CPU.
  3. mpe, Feb 26, 2018
    Last edited: Feb 26, 2018

    mpe macrumors 6502

    Sep 3, 2010
    There is almost no practical difference between these CPU parts in real world apps. If you want to split the hairs the gap between 3.4 and 3.5 is actually slightly bigger than between 3.5 and 3.8 GHz (in maximum turbo boost speed). However, don't spent your money to upgrade CPU in iMac unless you upgrade to 4.2 GHz i7 which is the only CPU upgrade that actually makes some difference.

    That's being said, the 3.8GHz configuration as offered by Apple is the best value as it also comes with (apart from the slightly faster CPU) with actually usable storage (2TB fusion) and improved graphics with more VRAM. I wouldn't buy any iMac with 1TB Fusion drive due to the tiny SSD in it.
  4. Ph.D. macrumors 6502

    Jul 8, 2014
    Just go with the base model. It's great. Use any left over funds for an SSD instead of a spinner.
  5. jerwin macrumors 68020

    Jun 13, 2015
    Of course, all four are vulnerable to SPECTRE/MELTDOWN, and all four are quadcore, not hexcore.
  6. Samuelsan2001 macrumors 604

    Oct 24, 2013
    My suggestion is unless you are going for the i7 then buy on the storage and gpu specs, you want at least a 2TB fusion but a pure ssd is better this should be your priority, GPU's are the most likely component to become a limiting factor with time so go for the best you can afford if you have any video editing or gaming or 3d modelling in mind.
  7. xzebra thread starter macrumors newbie

    Feb 20, 2018
    I personally would like the i7 but am worried about the high temp and fan noise on these. This would also give me the best graphics card.
  8. Samuelsan2001 macrumors 604

    Oct 24, 2013
    What do you use it for?? Information on what apps you use and how will you use them this info will give members a much better chance of advising you.
  9. xzebra, Feb 27, 2018
    Last edited: Feb 27, 2018

    xzebra thread starter macrumors newbie

    Feb 20, 2018

    Hi thanks for taking the time to help

    I would mostly use this for LR a bit of PS and regular everyday use (email, internet ect). I might play with the iMove app, although you won't get major video editing from me.

    I am concerned if I pull the trigger on a 4.2 - Heat and fan noise...seems to be a lot more of the 4.2Ghz in the refurb section....hmmm

    If I pull the trigger on 2/3 TB Fusion it will be slow....So many people say fusion is not good and so many say it is just fine. Hard to decide on this one. I would definitely hate to regret, but this could be a difference maker considering the upgrade price.
  10. mpe macrumors 6502

    Sep 3, 2010
    With all iMacs, you will experience fan noise under full load (or when you run a game or a batch export). Whether the i7 will be noisier than any of these i5's depends more on the actual load than on the CPU.

    Also, my experience is that there is a thing called "thermal paste lottery" when buying iMacs. If you are unlucky even the base i5 model can be hot and noisy.

    As for the storage, my experience is that 2TB or 3TB fusion is just fine for Lightroom (1TB is not). The fusion is doing more or less what you expect it to be doing (offload big masters to HDD while preserving your catalogue and previews on the SSD). It is a fun to watch it in iStats Menus that SSD and HDD are working together.

    The FD doesn't break record speeds, however, it doesn't feel slow. You get most benefits of SSD (mainly low latency and unlocking small I/O which is way more important than absolute speed) with much bigger capacity for money, In fact, the Lightroom works quite well even when masters are located on NAS which is even magnitude slower (latency-wise) than the FD. I would rather than a big internal fusion than a tiny SSD + bunch of external enclosures and permanently have to move stuff around.
  11. EugW macrumors 603


    Jun 18, 2017
    i7 will reach max fan speed in 30 seconds.
    i5 might take 8-10 minutes to get there.

    That can be a huge difference in real world usage, because the i7 will hit max fan with just heavier daily usage, whereas somebody with the same usage will never hit max fan with an i5 (particularly the 65 Watt models). Furthermore, this has been a pretty consistent observation. If there is a "thermal paste lottery", that has not proven to be as important to the actual CPU itself, i7 vs i5. Basically on average, judging by observations here, if you have very heavy CPU load:

    3.4 GHz i5 - You might be able to run this thing for extended periods without hitting max fan.
    3.5 GHz i5 - You can run this thing for short periods (many minutes) without hitting max fan.
    3.8 GHz i5 - You can run this thing for short periods (many minutes) without hitting max fan, but it might be a little quicker to hit max fan than the 3.5 GHz i5.
    4.2 GHz i7 - Will hit max fan within 30 seconds.
  12. wardie macrumors regular

    Aug 18, 2008
    I’ve got the i7 with 1TB SSD and my main use-case for computationally intense work is Lightroom. I added extra 16GB memory 3rd party to the base config, and couple extra USB3 HDDs for storage/backup. During editing I never find the fans spin up. It’s only when doing a batch operation like a big import or export that the fans crank up, and about after half a minute is probably right. But its not too noisy and often I leave it going on hundreds of images anyway and I’m not at it so I don’t care about the noise. It’s down to personal sensitivity whether the fans are a big deal to you, I don’t mind them they are not high pitched more or a whoosh noise (does that make any sense!?). On a batch run yes the temps get high with core 85-100C but I don’t really care as its all under AppleCare and if it fries I get it replaced. I’ve never fried a CPU despite I used to be into overclocked custom PCs etc. And the mac is operating under its normal parameters. But there are divided opinions on this as you can read elsewhere on the forum! Hope that helps.
  13. Samuelsan2001 macrumors 604

    Oct 24, 2013
    So a pretty easy use case that needs very little performance, buy whatever you want I doubt it will make much difference to you, the ssd is your most important thing. The 2/3TB fusion will be fast in most things and should be fine for your usage. I personally would get the 512gb ssd and store my media on external drives but that’s personal choice going forward 128gb of ssd may be your limiting factor.
  14. 06tb06 macrumors regular


    Sep 12, 2017
    2,711 miles from Apple Campus
    As mentioned in above posts:

    The 4.2GHz i7 will become toasty faster, then start throttling like crazy. The 3.8GHz i5 option is better in this regard--you'll be able to Turbo longer before throttling occurs. Also, given that most Adobe apps (including Photoshop) don't really utilize more than four processing cores, the i7 upgrade really won't matter that much.
  15. tomscott1988 macrumors 6502a


    Apr 14, 2009
    Lightroom is a hog. It needs a fast processor and a powerful graphics card to work anywhere near fluidly. Getting 100% previews on 25+mp cameras and making local adjustments is painful on most systems even with the 7.2 update.

    Get as much as you can afford. In terms of storage, as long as the library and smart previews are on the SSD it makes no difference to speed having the images on a spinner or SSD.

    The 2+3TB fusion drive can be a good area to save a little money and keep the desk clear of HDDs.

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14 February 26, 2018