Do You Need The Top iMac 5K for Gaming? Or Will A Lesser One Do?
Posted September 22nd, 2017, by rob-ART morgan, mad scientist
Do you need the 2017 iMac 5K with 4.2GHz Core i7 and Pro 580 GPU to get decent framerates when running the newest versions of serious games? Or will a lesser model with 3.5GHz Core i5 and Pro 575 GPU do just as well?
GRAPH LEGEND
1080 Ti iMac i7 - '2017' iMac 5K with 4.2GHz (4.4GHz Turbo Boost) Quad-Core i7 (7700K Kaby Lake) connected via Thunderbolt 3 to Sonnet eGFX Breakaway Box with NVIDIA GeForce GTX 1080 Ti (11GB VRAM) which, in turn, connected via dual DP cables to a Dell U2715K 27" display
Pro 580 iMac i7 - '2017' iMac 5K with 4.2GHz (4.4GHz Turbo Boost) Quad-Core i7 (7700K Kaby Lake) with AMD Radeon Pro 580 GPU (8GB VRAM)
Pro 580 Boost OFF - '2017' iMac 5K with 4.2GHz with Turbo Boost disabled*
Pro 575 iMac i5 - ''2017' iMac 5K with 3.5GHz (4.1GHz Turbo Boost) Quad-Core i5 (7600 Kaby Lake) with AMD Radeon Pro 575 GPU (4GB VRAM)
Pro 575 Boost OFF - ''2017' iMac 5K with 3.5GHz with Turbo Boost disabled*
*Turbo Boost was artificially disabled using Turbo Boost Switcher utility to simulate potential performance loss during extended 'heated' gaming sessions.
Total War: WARHAMMER - Using the built-in 'dwarfs versus greenskins' benchmark, we tested using the "High" preset, 2560x1440, full screen.
(HIGHER frames per second = FASTER)
X-Plane 11 - Using a recorded 2 minute flight of the SR-71 Blackbird, we launched the most stressful test (fps_test=3) from Terminal app specifying 2560x1440, full screen, circle view.
(HIGHER frames per second = FASTER)
How Hot Does The iMac's CPU Get?
HWMonitor reported the PECI CPU sensor's maximum reading during the third benchmark run.
How Hard Must The iMac's Fan Work?
HWMonitor reported the Main Fan sensor's maximum reading during the third benchmark run.
WHAT DID WE LEARN?
The 2017 iMac 5K Core i7 with Pro 580 GPU runs Warhammer 10% faster and X-Plane 6% faster than the 2017 iMac 5K Core i5 with Pro 575 GPU.
Assuming both models were configured with 16GB of memory and 1TB Fusion Drive, the 4.2GHz Core i7 model only costs $200 more. If the two games we featured represent the typical gamer's experience, then one must ask, "Is it worth spending 10% more to get 10% better gaming performance?" Probably.
The other deciding factor is heat. There are some who expressed concern that the 17% hotter running Core i7 might not be as reliable in the long term. If you think 212F CPU is hot, the GPU die sensor reported a constant 264F. Activity Monitor reported 30%+ CPU load (or 3 out of 8 hyper-threading cores) when running both Warhammer and X-Plane at our settings. OpenGL Driver Monitor reported 30-40% GPU load for Warhammer and 20%-100% GPU load for X-Plane. (Flying through clouds stressed the GPU most.)
Won't the 16% higher fan speed make the Core i7 model noisier? I suppose that depends on the amount of ambient noise. And if you are a typical hard core gamer that wears headphones, the iMac fan noise under stress is a non-issue.
We disabled* Turbo Boost to measure that effect. The iMac Core i5 3.50 GHz Core i5 with Turbo Boost rated at 4.1GHz (17% increase in clock frequency) gained only 4% in framerate at the expense of 6% gain in CPU temperature.
HOW DOES AN EGPU AFFECT PERFORMANCE AND HEAT? We included the results for the GTX 1080 Ti in the Sonnet eGFX Breakaway Box connected to the TB3 port of the iMac 5K i7. That setup ran as much as 16% faster while the iMac's Core i7 CPU ran 8% cooler and the fan stayed at 1200RPM idle. But, then the eGPU box and 1080 Ti GPU will add $1000 or 33 to 50% to your total system cost --- and that does not include the price of an external display which will be required if you expect the iMac 5K to use the eGPU's card when gaming.
WHERE TO BUY GPUS FOR MAC TOWERS AND EGPUS
MacVidCards sells the GTX 1080 Ti that includes Boot Screen support from all ports at Startup.
NewEgg sells the latest, fastest AMD and NVIDIA GPUs from various makers.
B&H Photo Video sells the GTX 1080Ti and other GPUs.
WHERE TO BUY Thunderbolt 3 GPU EXPANDER BOXES
Order the eGFX Breakaway Box direct from Sonnet Technologies. Pricing starts at $299.
The AKiTiO Node eGFX Box can be ordered from B&H Photo Video ($269).
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