New 2017 iMac 27" i7 vs i5 - heat noise and performance

[propower]

Hey all -

I am retiring my 2013 Mac Pro and am in love with the new iMac 5K 27"Screen. My needs are smaller than they used to be so I would like either the i7 or i5 to work for me. So I got both (i7 with 1TB SSD - i5 is stock) and have been testing them ...

The big bugger for me is I am a freak about fan noise. At idle the imac is perfectly fine with me. In simple testing I found that ~35% load on the i7 starts to ramp the fan and at 50% pretty much it maxes out. Also worth noting that 35% load puts temps near 95degC. The i5 (3.4GHz) on the other hand goes to 100% load and never exceeds 70degC.

I have mostly been doing acoustic music - very little VIs and less than 40 tracks (all 96kHz). Depending on the plugins sessions are running 25% on i7 (50% on i5). With the i7 the temps go to the mid 80s - on the i5 60degC. Note too that I am a freak on using low latency at 96kHz and am a bit wary of going 3.4GHz vs 4.2. Worth noting though that the i5 will Turbo to 3.8 (probably all the time) whereas the i7 when hot may simply remain at 4.2 - so less of a difference at least. In fact one of my temp strategies for the i7 is to turn Turbo off.

Although this is todays work I have a decent VI library and look to do more larger band type things and explore VIs...

So all indications so far say that the i5 would be enough - and i could save a bunch of cash waiting for iMac Pro or the new MacPro - maybe. I also am well familiar with "more cores for audio" mantra... but are times any different now??

[guitardom]

If a 35% load is running an i7 to 95c, either that Imac is horribly designed and I would not even consider using it (that is not good for the CPU to run that hot and will kill its life span) or you have a lemon that needs returned.

That being said, I would not rely on an i5. You are seriously hampering your abilities and overhead.

I don't think people are considering the fan noise these forthcoming Imac pro's are going to make by shoving a processor that requires that much power in such a small area, unless they downclock them.

[propower]

I have been having much discussion with folks on MacRumours about these machines and I am double checking PT again over the next few days. But the temps and loading is very consistent with other users of this one.

[guitardom]

Originally Posted by propower

I have been having much discussion with folks on MacRumours about these machines and I am double checking PT again over the next few days. But the temps and loading is very consistent with other users of this one.

That is crazy for the temps to be that high at 35% usage. I would NEVER ship a machine out the door that gets above 85c at 100% usage and they are typically under 80c. Many modern systems (not Mac) will actually shutdown the system to save it at around 90-100c.

[propower]

Every MBP i7 runs like this (though I am not sure at what load today). My old i7 MBP 13 (2013 and 2015) would do it at roughly the same place. Nothing new for Macs. MacPros are the exception with cooling that is almost never stressed. That's partially why AppleCare on iMacs is so key (IMO) and also why many at 2.5years sell them and replace with the newer model.

Other inputs? iMac users?

[propower]

Hey all - still struggling a bit with choosing the right iMac for myself. I am not restricted in cost but I hate ever spending more than what is needed if there is no clear benefit. I have demoed a few and here is where I am at

1) From the 3.4 i5 all the way to the 4.2GHz i7 - speed seems to make no difference to my PT or other DAW sessions. All tracks and plugins are running fine. No plugin that runs reasonably well at 96kHz/64buffer is taxing any of these any more than the other.

2) Turbo seems to make also - no difference.

3) Somewhere around 3.9GHz is where the cooling system starts to have trouble keeping the CPU at less than 80degrees (with heavy loads). I mostly turn Turbo OFF for the i7 and i5 3.8 since it only added heat - not performance. The i7 is by far the hottest and even with Turbo OFF - hits high fan speed for loads above 50%. My typical sessions would very rarely hit above 35% on the i7. All my music video renders will hit full fan on i7 in 30 seconds - no fan on any i5 with Turbo OFF on the 3.8.

4) The SSD is amazingly fast. Great for the OS - too small even at 1TB for the whole sample library. When does this amazing speed truly matter over lets say TB3 cage and a Samsung 850 (550 Read/ 450 Write).

Thanks!

[leftalive]

Originally Posted by guitardom

I don't think people are considering the fan noise these forthcoming Imac pro's are going to make by shoving a processor that requires that much power in such a small area, unless they downclock them.

Srsly. I watched the unveiling at WWDC and couldn't help but think 'Wow, that's an impressive list of specs, and you're going to be able to fry an egg on the back of one of those things'.



I don't know that I'd be able to get on with an AIO in a studio environment, due to the noise/heat issues, but if you're dead set on using one - and price isn't a consideration - I'd vote for the faster machine. They're both going to be loud and they're both going to run hot.

The extra juice will come in handy, especially when you start running VI's and plugins.

[propower]

oops - I just re-read and see you are talking about the iMac Pro...

Thanks for your input but I have tested both the i7 and the stock base model i5 in my studio environment. At idle fan speed the imac is very quiet. The i5 3.4GHz never goes above 60degC (100% load) and never ramps the fans. It also runs 40 instances of Kontakt at 96kHz (I usually use a few). It also runs LiquidSonics Seventh Heaven no problem. I have owned a nMP for 3 years. the new iMac even with a Fusion drive is easily as quiet. The i7 is also nice and quiet to about 35% load. from there up one can expect some to lots of fan noise.

I have ordered a 3.4GHz i5 with 256 SSD this morning.

[SigFriedChicken]

I have 2014 iMac i5 3.5 Ghz. I rarely ever hear the fan unless I've got some 3D graphics-heavy application running -- which is very rare.

I do wish I had sprung for the i7, but the added fan noise is concerning. iMacs are supposed to be whisper quiet. That's one of their advantages over most PCs.

[ronwasserman]

My Late 2014 5K 4GHz i7 with 1TB Flash doesn't make a sound unless I'm processing/converting video files. Right now it's at 120 degrees and the fan is at 1195 RPMs. I was using this for PT HDX but opted for a Trash Can Mac Pro just for the power. That one averages 107 degrees with the fan at 772 RPMs.