New 2017 BTO – 3.8 GHz i5 or 4.2 GHz i7?

Mejoco_LC475

macrumors newbie
Original poster
Jul 6, 2017
10
2
United Kingdom
First post, please be gentle! (posted in the the Apple discussion/community forums for years, but tend to avoid now).

I’ll shortly be pressing the button on a new 2017 BTO 27" iMac.

Initial spec/thoughts were as follows:

27”
4.2 GHz i7
Radeon 580
32 GB Ram
1 TB SSD

I’ve been lurking for a while just to gauge feedback on the new iMac models. Coming from a near silent late 2012 iMac I’m somewhat concerned about reported fan noise and heat from the i7 processor in the new models. I work in a small home office and love the silent operation of my current iMac.

This got me thinking, should I just stick with the 3.8 GHz i5 rather than the i7 4.2 GHz upgrade?

My work is 99% Adobe Creative Cloud (InDesign, Illustrator, Photoshop, Acrobat), although I’m planning on moving over to Lightroom from Photos. I don’t work with video (or Audio), just the occasional iMovie home project.

My current late 2012 iMac is silent and cool at all times, I’ve never heard the fans ramp up in 5 years of use. Here’s the spec:

Late 2012
27”
3.4 GHz i7
16GB Ram
750 SSD

It’s still a great machine, but I really need to hand this down to my daughter as the 2009 iMac she uses is really starting to show it’s age!

I understand Hyper-threading technology to a degree, but would there be any reason/advantage (based on my use) to go for the i7?

Thanks in advance!
 

Glideslope

macrumors 603
Dec 7, 2007
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A quiet place in NY.
Since you use mainly Adobe products then the CPU would most likely be an important factor. My understanding is that Photoshop uses Hyper Threading. This would dictate an i7. Some other products are much more GPU intensive. I have the i5 6700k in my 27" and have been very happy with it's performance with the SSD Drive. The i7 can get quite toasty quite quickly. The mid level 3.5GHZ i5 seems to be a nice compromise if you're not always riding a tight deadline. My 3.8GHZ has never been above 80c and idles around 28c. Remember the 580 will generate heat as well so you want to be careful.

Hopefully others with more editing experience will chime in. I'm a RAW person, and don't have much video experience. The 3.5GHz i5 is a very nice setup if you're not always in a rush. The 575 is a nice GPU, and generates less heat.

Goodluck. :apple:
 
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Moriarty

macrumors 6502
Feb 3, 2008
417
127
In situations where the i7 will make a noticeable difference in speed, you will also hear the fan ramp up. CPU-only load (e.g. encoding video) is enough to get the fan to spin at maximum speed (2700 rpm) on the i7, which is quite loud. Put the same load on the i5, and it'll still be at idle 1200 rpm. It'll do the job a little slower, but quietly.

The i5 models run much cooler and quieter. With your usage, you'll likely never hear the fan on the i5 + 580. You really need to push the CPU and GPU simultaneously, for a few minutes, in order to hear the fan on this model (e.g. gaming). Even then, the fan doesn't really go above ~ 2000 rpm, which is still fairly quiet.

I'd say get the i5. It's plenty fast enough.
 
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EugW

macrumors 604
Jun 18, 2017
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Why the 580? What about getting the i5-7600 with 575? Or is it more about getting the i5-7600K (which is only marginally faster than the 7600)?

Also, why not get 8 GB RAM and then another 32 GB Crucial RAM? Don’t pay Apple’s RAM prices.

BTW, a friend of mine is a pro CC guy and does well with a 2014 i5-4690 and 24 GB.
 
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PJivan

macrumors 6502
Aug 19, 2015
456
431
My i5 3.8 with 580 is silent even after 4 hours of play with Warhammer total War....quite happy with that
 

FastEddiebags

macrumors 6502
Jun 1, 2012
336
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NJ
Agree with above about getting after market ram. Take advantage of the one easy thing you can upgrade yourself.
 

PJivan

macrumors 6502
Aug 19, 2015
456
431
Since you use mainly Adobe products then the CPU would most likely be an important factor. My understanding is that Photoshop uses Hyper Threading. This would dictate an i7. Some other products are much more GPU intensive. I have the i5 6700k in my 27" and have been very happy with it's performance with the SSD Drive. The i7 can get quite toasty quite quickly. The mid level 3.5GHZ i5 seems to be a nice compromise if you're not always riding a tight deadline. My 3.8GHZ has never been above 80c and idles around 28c. Remember the 580 will generate heat as well so you want to be careful.

Hopefully others with more editing experience will chime in. I'm a RAW person, and don't have much video experience. The 3.5GHz i5 is a very nice setup if you're not always in a rush. The 575 is a nice GPU, and generates less heat.

Goodluck. :apple:
Just as FYI the 580 runs very cool...not sure what they did there but it's the coolest top level gpu I ever saw on an imac....way more than 395x, 780m and old radeon.
 

EugW

macrumors 604
Jun 18, 2017
7,312
4,692
Just as FYI the 580 runs very cool...not sure what they did there but it's the coolest top level gpu I ever saw on an imac....way more than 395x, 780m and old radeon.
As mentioned, this series is a result of two whole node shrinks in the chip manufacturing process. That’s huge. With each node shrink there is usually a significant decrease in power utilization, but this generation got two node shrinks.

Also, the 580 (like many other Apple GPU parts) is underclocked, further decreasing power utilization.
 

EugW

macrumors 604
Jun 18, 2017
7,312
4,692
Which is interesting because both CPUs (i7-7700K / i5-7600K) have the same 91W TDP. I'm guessing the i5 never hits that even under maximum load due to the lower clock speeds?
Never say never, but the 7600K is lower clock speed than the 7700K and has no Hyperthreading.

Initial testing suggests the 7600K behaves more like the 7600 but has the potential in extreme loads in some reviews to get significantly hotter than the 7600.
 

Bob418

macrumors member
Sep 10, 2015
42
24
Singapore
Which is interesting because both CPUs (i7-7700K / i5-7600K) have the same 91W TDP. I'm guessing the i5 never hits that even under maximum load due to the lower clock speeds?
What you guess is basically right. The 7600K is an unlocked chip. Its higher TDP is mainly for overclocking purpose. But in iMac, you don't have chance to overclock the CPU. So its difficult for it to hit the highest TDP, unless in turbo mode for long time.
 

mollyc

macrumors 68020
Aug 18, 2016
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I have basically the same 2012 model (but a fusion drive), and I just ordered the 2017 i7/580 model with the 1TB SSD. I will add in memory on my own. I also love my near silent 2012 model, but I keep computers for a long time, and am only upgrading because my kids need a newer version than the 2008 model they currently use. So they will get the 2012 and I will move to the 2017. I got the i7 because programs are only going to need more computing power down the road, so wanted to ensure something that lasts at least 5 years again.

I also spend my days in PS/Bridge/LR with very little video production.
 

EugW

macrumors 604
Jun 18, 2017
7,312
4,692
I have basically the same 2012 model (but a fusion drive), and I just ordered the 2017 i7/580 model with the 1TB SSD. I will add in memory on my own. I also love my near silent 2012 model, but I keep computers for a long time, and am only upgrading because my kids need a newer version than the 2008 model they currently use. So they will get the 2012 and I will move to the 2017. I got the i7 because programs are only going to need more computing power down the road, so wanted to ensure something that lasts at least 5 years again.

I also spend my days in PS/Bridge/LR with very little video production.
The benefits of the i7 may not be all that great for you then. For the most part, PS and LR are not very well multi-core optmized. The 7700K on average gets you about 5-10% more performance over the 7600K. Sometimes more, and sometimes less.

Lightroom:

https://www.pugetsystems.com/labs/articles/Adobe-Lightroom-CC-2015-8-Intel-Core-i7-7700K-i5-7600K-Performance-880/

Lightroom.jpg


Photoshop:

https://www.pugetsystems.com/labs/articles/Adobe-Photoshop-CC-2017-Intel-Core-i7-7700K-i5-7600K-Performance-879/#Conclusion

Photoshop.jpg


More Photoshop:

http://www.tomshardware.com/reviews/intel-kaby-lake-core-i7-7700k-i7-7700-i5-7600k-i5-7600,4870-6.html

aHR0cDovL21lZGlhLmJlc3RvZm1pY3JvLmNvbS9CL1IvNjM5MzUxL29yaWdpbmFsLzA2Yi1BZG9iZS1QUy1IZWF2eS5wbmc=.png


In contrast, in stuff like software 3D rendering, the 7700K totally destroys the 7600K.

Cinebench:

http://www.tomshardware.com/reviews/intel-kaby-lake-core-i7-7700k-i7-7700-i5-7600k-i5-7600,4870-4.html

aHR0cDovL21lZGlhLmJlc3RvZm1tTXVsdGktQ29yZS5wbmc=.png
 
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propower

macrumors 6502a
Jul 23, 2010
719
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I have always had i7's at least and Hex cores or multi CPU old style server grade things. I just ordered a 3.4GHz i5 with 256 SSD because in all my testing for audio work - if I can fit my session in an i5 - (which is 100% true today with lots of margin to spare) I found zero meaningful performance difference in anything faster. All the i5s run way cooler and the tipping point with clock speed versus thermal handling is ~3.8GHz. The base model with all cores loaded Turbo's to ~3.65GHz and never goes over 60degC. The 256GB internal was chosen for cost and the reality that I have 1TB+ of samples and Audio Files that will never fit on even the 1TB internal. My OS drive on the other hand is max ~150GB. With a TB3 external cage for SSDs (I have many SSDs already) I get 4 full speed SATA drives for ~$350 (the cost of the cage). Even without - my existing TB2 4 drive cage gets 350MB/s R/W. Totally serviceable for what I do.

With this "low" entry cost - I will also feel no remorse if 1 year from now I jump to what's new and better :).

SO - IMHO - if you don't "need" an i7 - the i5s are lots of computer without the added heat and potential fan noise. Also - in all my searching and testing I just can't find any difference in non professional video editor use between any of the three video options. Even in the pro use - I am unclear when any of the video options matter. I concluded that if I couldn't figure that out - it must not matter to me. In my use of doing imovie transcodes for music video posts I found the i7/580 12% faster than the i5/570. Just not a meaningful difference to me.

There is much more video oriented information in this thread should video be the tipping point of which iMac to get... https://forums.macrumors.com/threads/the-new-imac-is-a-lot-noisier.2051501/page-27
 
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xWhiplash

macrumors 68000
Oct 21, 2009
1,801
709
Which is interesting because both CPUs (i7-7700K / i5-7600K) have the same 91W TDP. I'm guessing the i5 never hits that even under maximum load due to the lower clock speeds?
Intel confirmed that the 7700K and the 7700 can spike 30 degrees Celsius just by opening a website. This is why people here have reported that it gets hot FAST. Difficult for the fans to keep up. Intel considers this normal. The fans need to keep up. As long as your iMac is not shutting itself off, the i7 is still within the thermal limits and is fine.
 

joema2

macrumors 68000
Sep 3, 2013
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Intel confirmed that the 7700K and the 7700 can spike 30 degrees Celsius just by opening a website.... Difficult for the fans to keep up....
I have never heard the fans in my 2017 iMac 27 i7 spin up from merely opening a normal web site. If that web site is a Youtube page streaming 8k video (which an i5 cannot even play smoothly), yes in that case the i7 will spin up until High Sierra ships in a few months then Safari will use Quick Sync and run cooler and quieter.

Normally you don't hear the fan in the i7 Mac. If you do sustained video transcoding you will certainly hear it. Based on your sensitivity and presence/absence or masking room noise, it can get annoying. For people that are noise sensitive the 2017 3.8Ghz i5 is a good alternative -- it is still pretty fast.