575 or 580 with i5?

>I am thinking of the 580

Sounds like you might add extra monitors now or down the road?

I am going with the 580 since I will be adding 2 4K monitors and my pet peeve is a slow to respond "Mission Control".

that's why I am throwing as much GPU at the thing as i can.

I -believe- unless you play games, or render video in your case, the 580 would not add that much heat compared to the responsiveness it could - should add to your new system.

Ask yourself. In one year will you be mad at yourself if you DONT buy the 580?

 

575 may be fine, but if the little one wants to game on it, then 580 would be an advantage.

https://support.apple.com/en-ca/HT201918

Assuming I have the right chips:

2011 i7 4.2 GHz 7700K is a 91 Watt TDP chip, but the iMac idles at 71W, and the overall power used is up to 217W.
2013 i5 3.4 GHz 4670 is a 77 Watt TDP chip, but the iMac idles at 80W, and the overall power used is up to 214W.
2011 i7 3.4 GHz 2600 is a 95 Watt TDP chip, but the iMac idles at 142W and it consumes up to 200W max.

What does this mean exactly? Not sure, but something is off with that machine as it idles at 142W! No wonder you had heat related problems with it. Interestingly, the 7700K is the lowest at idle out of the three models.

What I can say is that for 98% of what I do, the 2017 i7 4.2 GHz 7700K iMac is silent. However, if I do any video encoding, then the fan ramps up.

As for Photos, based on my limited testing at home and at the Apple Store, it seems the most significant factor for UI speed is whether or not you have an SSD, cuz a MacBook Pro with SSD feels noticeably faster for UI navigation (scrolling and previews) in Photos than a 3.8 GHz i5 with Fusion Drive.

24 GB seems plenty.

So, I'm happy with the i7 7700K with 580, but if you want to be 100% sure it's always quiet, then maybe consider the i5 7600 non-K with 575.

 

>What I can say is that for 98% of what I do, the 2017 i7 4.2 GHz 7700K iMac is silent. However, if I do any video encoding, then the fan ramps up.

Just wondering. Are you in an Air Conditioned environment?

thx.

 

Yes. Max temp may be 24-25C, but it was probably only up to 23C when I was testing out the iMac.

 

Based on just raw specs, the Radeon Pro 580 is a fair step up from the RP 570.

As for CPUs, I always go for the i7, but for what I do, the i5 would probably be plenty and it runs a fair bit cooler under load.

 

It is tough decision to make because the price between the above two configuration is pretty close, at least in my country. The CPU improvement is minimal but the GPU upgrade is quite good. Is GPU a major consideration if I want to connect to 4K monitor to the iMac in future? Or 575 should handle it well?

I am glad you are able to make your decision. I hope to make mine by end of this week.

 

Best bang for the buck, IMO.