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Smoothie

macrumors 6502a
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Jun 23, 2007
781
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California
I'm planning on getting the new iMac, and I've got the configuration chosen except for the CPU. I've done a lot of research on the 7700K, and it seems to run very hot under load. It's rated for a maximum temp of 100 deg. C, and many tests have shown it to operate near that limit when pushed. I know the chip will throttle back to preserve itself, but then you lose the benefit of the rated clock speed. Also, the surrounding electronic components are subjected to the heat.

I have a PC that I built a couple of years ago with an Intel 4790K (also 4 cores with hyperthreading and an 8 MB cache), and it never goes above 70 deg. C when being stress tested. My PC has two fans on the CPU heat sink (air cooled only), and three case fans. Even with all those fans, it's fairly quiet (expensive fans). I would never want a CPU to operate so close to its Tjunction limit. The iMac has a very hot chip in a small case with one fan, and that concerns me.

The 7600K operates at lower temps than the 7700K, according to tests I've seen. I assume the slightly lower clock speed and lack of hyperthreading contribute to that. So here's my dilemma. I believe Logic can take advantage of hyperthreading, but I'm not planning on creating projects with dozens of tracks. So for those Logic folks out there, do you think the 7600K would do the job? I've actually used Logic on a 2009 Macbook Pro with a chip with two cores and no hyperthreading, so anything would be significantly better than that.
 
You might want to check out the iMac noise thread, particularly propower's posts, like these ones here and here.

I don't know much about Logic Pro X, so I defer to his posts, but he notes that in the more significant load tests the CPU usage can go over 50% and eventually the fan can ramp up to around 2000 rpm on the Core i7-7700K. That is not max fan noise, but it is audible. In contrast, 1200 is inaudible to most.

If you turn off Turbo for the Core i7 7700K (but leaving HT intact) using Turbo Boost Switcher, the chip runs cooler, and at least in his test it made a significant difference for CPU temp and fan speed. Furthermore, you can also turn off HT as well, although that requires installing Xcode.

However, if you are going to be turning off HT and Turbo on a regular basis you may just be better off getting an i5 of some sort. I suspect if you had an i5-7600K, which is still a very decent chip, it'd probably run cooler to begin with (even though it is also a 91 Watt TDP chip like the 7700K) and if necessary you could turn off Turbo to further decrease the temps. Since the 7600K does not support HT, you wouldn't have to worry about that.

Unfortunately, if you ever do any video encoding, you'd want to have HT. For example, in many tests, the 7700K is roughly 30% faster than the 7600K in multi-threaded video encoding. Yes, that does turn on the fan, and it can ramp as high as 2700 rpm (max) which is moderate noise, but for video encoding that's not a big deal IMO.
 
I have done some testing on the 7500 and 7700K. The big thing is that the cooling system for all of the iMacs is the same. It does a phenomenal job on the 7500 (i5 3.4GHz). 100% load gets to 60degC from about 40degC at idle. Fan never moves off of 1200rpm. The 7700K will go to maximum fan somewhere between 30% and 50% load. Still working on where this cut off is.

In Logic - I ran a 100 Audio track test with 4 drummers a reverb and 300+ plugins. 50% load on the i5, 50degC CPU. Same test on the i7 29% load, 77 to 88degC peak temps. The i7 was already close to where the fan would ramp up, the i5 had 50% more CPU to go.

I am currently checking ProTools performance and in general am finding the same trend - not ready to publish this yet though.

WRT video encoding (music videos) - all I do is 1080P camera + audio from logic or Pro Tools that is put together in iMovie or now Davinci Resolve for 720P Youtube videos. A 12minute video encode was 12% faster on the i7/580 vs the i5/570. 4min 20 sec vs 3 min 50sec. The fan kicked on after 2 minutes of the i7 - i5 never went above 60degC. Its not a bad fan but for audio mixing or recording I tolerate nothing above the idle 1200rpm...

my 2 cents :)
 

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I have done some testing on the 7500 and 7700K. The big thing is that the cooling system for all of the iMacs is the same. It does a phenomenal job on the 7500 (i5 3.4GHz). 100% load gets to 60degC from about 40degC at idle. Fan never moves off of 1200rpm. The 7700K will go to maximum fan somewhere between 30% and 50% load. Still working on where this cut off is.

In Logic - I ran a 100 Audio track test with 4 drummers a reverb and 300+ plugins. 50% load on the i5, 50degC CPU. Same test on the i7 29% load, 77 to 88degC peak temps. The i7 was already close to where the fan would ramp up, the i5 had 50% more CPU to go.

I am currently checking ProTools performance and in general am finding the same trend - not ready to publish this yet though.

WRT video encoding (music videos) - all I do is 1080P camera + audio from logic or Pro Tools that is put together in iMovie or now Davinci Resolve for 720P Youtube videos. A 12minute video encode was 12% faster on the i7/580 vs the i5/570. 4min 20 sec vs 3 min 50sec. The fan kicked on after 2 minutes of the i7 - i5 never went above 60degC. Its not a bad fan but for audio mixing or recording I tolerate nothing above the idle 1200rpm...

my 2 cents :)
The issue I had with the i5-7500 was that it was only about 40% faster than my existing old 2010 Core i7 iMac overall. The new Core i7 is twice as fast. ;) However, I don't do pro audio, so the occasional fan ramp up doesn't really bother me.

And as mentioned in the other thread, video encoding performance varies, but the Core i7 might be up to 50% faster than the i5-7500 in some cases.

BTW, for the OP I guess I should point out that there are two classes of chips in the 27" iMac:

i5-7500 - 65 Watt TDP
i5-7600 - 65 Watt TDP
i5-7600K - 91 Watt TDP
i7-7700K - 91 Watt TDP

propower's results reflect this. Furthermore, he is testing the slowest 27" iMac CPU vs. the fastest 27" iMac CPU. The other two chips will be in between.

Too bad Apple doesn't sell an iMac with the 7700 (non-K). It's a 65 Watt chip, yet competes against the 7600K for performance. If an iMac i7 7700 had existed, I would have bought that one. It's 3.6 GHz with Turbo boost up to 4.2 GHz, but with hyperthreading and 8 MB L3 cache. The 7600K is 3.8 GHz with Turbo boost up to 4.2 GHz, no hyperthreading, and 6 MB L3 cache.
 
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The percentage faster do not seem to be translating to audio work for me yet. Looking at the audio loading from Logic (now this is total CPU so there is overhead as well) but - i7 was 29% (of 8 cores) and i5 was 49% of 4 cores. No apparent advantage to the 40% faster speed of the i7! Still more to test and think about and test for me (I am an Electronics Engineer not a Computer Engineer :). Now if my sessions would not fit on 4 cores that is a reason to have more in my case. The raw speed difference seems to have minimal effect on things I do...

Also, when i went to the MacPro in 2014 I tested the top of the line iMac against it and the MacPro was a clear winner. It was how it worked as a complete system - not any individual part. The temperature performance was always stellar but for low latency audio work in Pro Tools then - there was virtually no CPU spiking whereas on the iMac there still was. Thinking that a system is only 40% faster based on CPU GHz is not how I see it. All the surrounding systems also service the users needs. I/O, bus speed, memory, SSD etc... For my work - the new iMac is much faster in many ways - CPU is just one of them. Compared to the nMP I have - the 3.4GHz cpu is slower - but the overall iMac performance is much faster. I am working on a test in Pro Tools showing that the nMP takes 25% of 12 cores (6 cores with HT) to do what the iMac i5 does with 56% of 4 cores :)
 
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Thanks for the good info EuqW and propower. It's too bad Apple didn't offer a 7700 which wasn't unlocked. iMac users aren't going to overclock their CPU anyway. I'm actually not overly concerned about the fan noise since I usually wear headphones when running Logic anyway. But I am concerned about why the fans ramp up; i.e., the rising temps that approach the maximum rated temp. The beautiful slim design of the iMac, with barely visible openings, makes keeping the CPU, GPU, and power supply cool very challenging.

Even though the 7600K has a TDP of 91 watts, like the 7700K, it doesn't seem to come close to generating the same amount of heat. And I don't think I'd want to turn off Turbo and hyperthreading to have the 7700K run cooler, since you buy a chip to use its full potential. I'm really leaning in favor of the 7600K. Propower seems to be able to run lots of tracks and plugins in Logic with the lower tier i5, so the 7600K should handle that just fine.
 
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Thanks for the good info EuqW and propower. It's too bad Apple didn't offer a 7700 which wasn't unlocked. iMac users aren't going to overclock their CPU anyway. I'm actually not overly concerned about the fan noise since I usually wear headphones when running Logic anyway. But I am concerned about why the fans ramp up; i.e., the rising temps that approach the maximum rated temp. The beautiful slim design of the iMac, with barely visible openings, makes keeping the CPU, GPU, and power supply cool very challenging.

Even though the 7600K has a TDP of 91 watts, like the 7700K, it doesn't seem to come close to generating the same amount of heat. And I don't think I'd want to turn off Turbo and hyperthreading to have the 7700K run cooler, since you buy a chip to use its full potential. I'm really leaning in favor of the 7600K. Propower seems to be able to run lots of tracks and plugins in Logic with the lower tier i5, so the 7600K should handle that just fine.

With a higher clock speed and hyper threading, I think it is pretty normal for it to be hotter than the slower i5 version. Then again, due to its better performance, tasks get executed faster. So for example, i7 may take 30 seconds to execute a task at 90C while i5 may take 45 seconds to do it at lower temperature (e.g 60C). It is only worrying if it maintains at high temperature (> 70C) throughout the entire day which is definitely not good for the hardware.
 
Audio multitrack recording and mixing represents a constant load in any given session that increases with tracks or plugins. In testing on the 2017 i5 and i7 imacs I find a moderate session to be in the 20% range on an i7 (40% on i5). A heavy session will be more like 30% i7, 60% i5. 85 to 95degC i7, 45 to 55degC i5.

I wish Apple would have had the option for an i7 7700 nonK!
 
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Audio multitrack recording and mixing represents a constant load in any given session that increases with tracks or plugins. In testing on the 2017 i5 and i7 imacs I find a moderate session to be in the 20% range on an i7 (40% on i5). A heavy session will be more like 30% i7, 60% i5. 85 to 95degC i7, 45 to 55degC i5.
I guess the question is if you have anything that the i5 can't handle. If not then perfect.
 
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IT's for audio, it honestly doesn't matter.

Actually in Audio the CPU is the most important thing, in difference to video editing Audio is all about real time performance, its not like it just takes longer.

Audio can knockdown any cpu easily, Audio needs TONS of performance, depending on what you do.

Latency wise the 7700k is the best cpu available.

there is a huge difference in Logic between the i5 and i7.

The K is not just about overclocking. the k has nearly 1 Ghz higher base clock speed.

anyway the non K is not available so .....


the i7 is the better choice for sure
 
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Indeed, the wondering! The awesome tests you and propower have shared would be great to know on the little 65watter. But then its the Radian 550 or 560. BTO gets pricey quick adding ram. Then a second monitor, I guess.
21.5, 512SSD, R560, 32GB $2600. Drop to 16GB is $2200 if I looked it up correctly.
 
I guess the question is if you have anything that the i5 can't handle. If not then perfect.
Exactly (I think)

Actually in Audio the CPU is the most important thing, in difference to video editing Audio is all about real time performance, its not like it just takes longer.

Audio can knockdown any cpu easily, Audio needs TONS of performance, depending on what you do.
Latency wise the 7700k is the best cpu available.
there is a huge difference in Logic between the i5 and i7.
The K is not just about overclocking. the k has nearly 1 Ghz higher base clock speed.
anyway the non K is not available so .....
the i7 is the better choice for sure

OK - I have thought exactly the same for 20 years and now I am staring at the base i5 and the i7 iMacs in house and can't prove it. Can you give me a sample Logic session with standard Logic plugins and VIs (minimal audio - not trying to steal anything) - that will Show just how much better the i7 is. In my 100+ Audio track 300 plug in + 4 drummers test with Logic the i7 was literally using 1/4 the available 8 cores and the i5 used 1/2. Huge difference in CPU speeds - no difference in CPU usage. Would be very much appreciated.

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PS - the 27" 5K screen is actually 1/2 the reason for me to get this one. Also the heatsinking on the 27 is vastly different. Still - I would love to see temp tests on the top 21.5 :)

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PSPS - I would also love a max load temp test on the top i5 to see if that one also kicks the fans or can you go 100% with no increase in fan speed
 
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Figured I'd post in this thread (as opposed to the "imac is noisy" thread, since the people in this thread are focused on Logic Pro, which is what I'll be focused on.

Waiting eagerly for my i7 580 to arrive (1TB SSD, will upgrade the RAM myself at some point). All the conversations about the i7 and fan noise has given me (as it has others) pause.

propower (and others): is there a simple logic session you could provide me (once I get my system), that I could easily load and verify the fan noise when the fan kicks in at high temps? I basically want to understand how loud the fan is going to be, and if it'll annoy me, within the 14-day return window...so I could return and get an i5, if need be.

Thanks to all...I've been following this thread (and the "noisy" thread) with much anticipation.

Chris
 
I have just made a silly sounding Logic file to test the difference between the i5 and i7 machines
Its 5 VI tracks (128 buffer 96kHz) and then duplicate...
With 42 of these going the i5 is 50% CPU (90% on the Logic CPU monitor) and 56degC nice and steady
But any more and Logic will throw an overload error and stop

With 100 of these going the i7 is also around 50% load (90% on the Logic CPU monitor) and plays no issues. More than this gets stops. Temps hover around 95degC and fan settled in around 1600 (erratic). I set the fan to 1800 via istat but temps were still peaking in the 90s.

If I was an orchestral guy I would go MacPro and as many real cores as I could. For my uses - 40+ VI tracks would be a huge number. I am more a real instrument guy though. It is fascinating to see where the i7 really shows its stuff - but the temps are nowhere near controlled compared to the i5. I love the headroom of the i7 but I may make the tradeoff and have to freeze more if I get at all close to the limits... More work to do...

If you promise not to turn the sound on past a whisper I will share this file. Silly crap done with computer keyboard entry... laugh out loud but no critiques please :)!

https://www.dropbox.com/s/bbp5ahfr6u6tsmu/LogicTest2VI.logicx.zip?dl=0
 
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I have just made a silly sounding Logic file to test the difference between the i5 and i7 machines
Its 5 VI tracks (128 buffer 96kHz) and then duplicate...
With 42 of these going the i5 is 50% CPU (90% on the Logic CPU monitor) and 56degC nice and steady
But any more and Logic will throw an overload error and stop

With 100 of these going the i7 is also around 50% load (90% on the Logic CPU monitor) and plays no issues. More than this gets stops. Temps hover around 95degC and fan settled in around 1600 (erratic). I set the fan to 1800 via istat but temps were still peaking in the 90s.

If I was an orchestral guy I would go MacPro and as many real cores as I could. For my uses - 40+ VI tracks would be a huge number. I am more a real instrument guy though. It is fascinating to see where the i7 really shows its stuff - but the temps are nowhere near controlled compared to the i5. I love the headroom of the i7 but I may make the tradeoff and have to freeze more if I get at all close to the limits... More work to do...

Thanks for putting the effort into this! A few questions/comments:

1) I'm new to all this, but is the logic file test you made something that can easily be shared? My reason is for asking is because I've never used Logic Pro, but I want to hear (as soon as possible after getting my i7) what the higher fan speeds sound like with a heavy-weight Logic file playing. If I could quickly load up the test file you made, that would be awesome.

2) Initially, I was planning to go MacPro with 6 cores. But considering the last hardware refresh of those was 2013, and who knows when they'll release the next (next year maybe?), and the iMac Pro looks overkill even for me, I chose to take the plunge now. I figure the i7 with HT would give me a decent amount of performance.

3) Even in orchestral stuff, with something like 80-90 tracks, I can't imagine all of those tracks are playing simultaneously. But obviously, want to know what really pushing Logic to the limits is going to do in terms of fan speed/noise.

Thanks again,

Chris
[doublepost=1498508432][/doublepost]I see you just posted the file...thanks! Quick question: do I need anything other than the "stock" stuff that comes with Logic Pro X to use this? (i'm assuming not)
 
Funny - I have had the MP Hex for several years. Great machine. I uploaded a file you can use. You can also use istat and set the fans. The i7 with 100 VI tracks at once was at its limit (with 128 buffer and 96kHz) per the Logic CPU meter. The fan was around 1600 and not bad. For quiet recording in the same room it would suck. As a recovering EE designer I hate seeing a thermal design that lets parts shoot from 40degC to 95degC. Any gamer would replace that cooling system pronto! But it really does take a pretty extreme Audio load to keep the i7 fans up at 1800 or louder. For me anything past ~1600 is annoying if constant. Huge preference for 1200rpm. The MacPro never went past base fan speed for me - 60degC was impossible for me to exceed with audio or simple video work.

--- Just stock logic stuff (though I did download a bunch of their extra content too).
 
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Awesome. I don't plan on doing any live recording of audio in the same room as the iMac, and admittedly will probably be using Beyerdynamic headphones a lot of the time that I'm composing, but it's more just to see how annoying/loud the fan truly is. I can be sensitive to that sort of thing, but if you say "fan was around 1600 and not bad" for 100 VI tracks, that's pretty darn good enough for me, I'd think.
 
If you promise not to turn the sound on past a whisper I will share this file. Silly crap done with computer keyboard entry... laugh out loud but no critiques please :)!

https://www.dropbox.com/s/bbp5ahfr6u6tsmu/LogicTest2VI.logicx.zip?dl=0

For the heck of it, I just tried playing your Logic file on my old mid-2009 MBP with a dual core 2.53 GHz chip. The poor MBP clutched its chest and keeled over as soon as I hit play. So I never got to hear your test sample. At least I know that the i5 will handle 42 tracks, which is more than I'd ever use.
 
Actually in Audio the CPU is the most important thing, in difference to video editing Audio is all about real time performance, its not like it just takes longer.

Audio can knockdown any cpu easily, Audio needs TONS of performance, depending on what you do.

Latency wise the 7700k is the best cpu available.

there is a huge difference in Logic between the i5 and i7.

The K is not just about overclocking. the k has nearly 1 Ghz higher base clock speed.

anyway the non K is not available so .....


the i7 is the better choice for sure

Sorry, was only talking from experience using different iMacs for a project where i was helping them with logic, i noticed no difference between i5 and i7
 
PS - FWIW on my VI test my old MacPro Hex 2013 did 108 tracks (just about maxing out all 12 cores 6 real 6 HT) - no stops - barely 50degC CPU - fan never budges on that one - ever. So where can I get a screen for that one that equals the iMac 27 ???
 
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