New iMacs which will run coolest?

nedlah said:

Anyone like to venture thoughts and speculations on this with the various gpu/cpu configurations- in general use and/or intensive

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How hot a Mac runs has far more to do with the workload you put on it than the specific configuration.

nedlah said:

So I guess that most heat would come from the gpu working overtime - thought maybe one had the edge over the others on the production of heat. Does that mean that generally any advantage one combination has over another in regard to production of heat is not going to be significant overall? What about running video off net(not hd). I guess intensive gaming is going to ramp up heat.

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The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source: Intel)

If you're not already using it, iStat Pro (free) or iStat Menus ($16) will give you accurate readings of your temps and fan speeds, among other things.

Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level.

If your fans are spinning up without increased heat, try resetting the SMC.
(PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

Learn about the fans in your Mac
Apple Portables: Operating temperature

For Flash-related issues:

• Find your Flash version and make sure it's the latest version available.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Use the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.)

I would venture.....

some thoughts about the topic. In my experience, a computer design too tight would run in heat dissipation problems when overload and/or overused. Comes to my mind intensive CPU/GPU operations, and in some cases, HDD intensive write/read operations. The new iMac, being a new design and looking after a brief view as closely packed would put itself in the situations I had commented. But not knowing the internal schematics, I would give Apple engineers the benefit of doubt