iMac, Logic Pro and virtual instrument libraries

[JVNeumann]

So, after going back and forth on waiting for the iMac Pro or long-prophesied Mac Pro, I've decided I'll probably get a 2017 iMac and fill it up to the gills with (third party) RAM to use as my next Logic Pro-focused machine. What I'm still on the fence about is how to approach the HD, especially as I have the better part of a terabyte of virtual instrument libraries to factor in.

I'm not really feeling masochistic enough to go for a 1TB SSD, and I'm actually already running a clean version of MacOS from an external SSD right now in my current iMac. So I'm wondering if I should just plug that same external MacOS SSD into the 2017 iMac, and just choose a big Fusion Drive to dump all my libraries onto (as well as photos, mail etc) - thus never actually using the internal drive to run the OS or apps from? I guess my main concerns are:

1. Does running the OS/apps from an external SSD come at any cost, relative to having them on an internal drive? Is that USB going to be bottle-necking me?
   
2. Does having libraries on Fusion rather than SSD really matter much, or is having MacOS and Logic Pro on a SSD the biggest factor here?
   
3. (bonus question) Assuming an i7 processor for both, would a Radeon 580 present any major thermal/noise problems that a 575 would not?

Thanks!

 

[propower]

So, after going back and forth on waiting for the iMac Pro or long-prophesied Mac Pro, I've decided I'll probably get a 2017 iMac and fill it up to the gills with (third party) RAM to use as my next Logic Pro-focused machine. What I'm still on the fence about is how to approach the HD, especially as I have the better part of a terabyte of virtual instrument libraries to factor in.

I'm not really feeling masochistic enough to go for a 1TB SSD, and I'm actually already running a clean version of MacOS from an external SSD right now in my current iMac. So I'm wondering if I should just plug that same external MacOS SSD into the 2017 iMac, and just choose a big Fusion Drive to dump all my libraries onto (as well as photos, mail etc) - thus never actually using the internal drive to run the OS or apps from? I guess my main concerns are:

1. Does running the OS/apps from an external SSD come at any cost, relative to having them on an internal drive? Is that USB going to be bottle-necking me?
   
2. Does having libraries on Fusion rather than SSD really matter much, or is having MacOS and Logic Pro on a SSD the biggest factor here?
   
3. (bonus question) Assuming an i7 processor for both, would a Radeon 580 present any major thermal/noise problems that a 575 would not?

Thanks!

You might want to read through the i7 is noisier thread...

1 - external SSD for OS works fine. The internal SSD option for these is almost 10X faster - much better.
2 - Libraries on Fusion is no problem - but if you need to load big things read and write on the Spinning part is ~120MB/s.
3 - 580 is not the heat source unless you do video. The K versions of the CPU bot i5 and i7 are the only ones that can heat up and make fans spin. The i5 3.4 never gets over 70degC and never ramps the Fan even at 100% load.

 

[JVNeumann]

1 - external SSD for OS works fine. The internal SSD option for these is almost 10X faster - much better.2 - Libraries on

So if I understand you correctly here, you're saying that an internal SSD will outperform my current external SSD? Because if that's the case, I would probably change my original plan and not use my external to boot the OS from.