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BARE FEATS LAB - real world Mac speed tests

Performance Analysis of The
'Best' 2019 iMac 27-inch

March 28th, 2019 by rob-ART morgan, mad scientist
March 30th - Added Geekbench GPU Compute Scores
April 17th - Replaced Geekbench Browser Scores with those from our test Macs

Last week some key upgrades have been announced to the iMac 27" with Retina 5K display. Two options that stand out relate to CPU and GPU. Let's discuss.

NEW CPU OPTION

The Intel 8-Core i9 3.6GHz processor is now the top CPU option for the iMac 27". It's the first time an 8-core CPU has been offered for the iMac. Plus faster 2666MHz DDR4 memory has been included.

Does this new CPU option bring the iMac 27" closer to the performance of the iMac Pro? Below are the best Geekbench CPU scores we recorded in our lab.

2019 iMac 27-inch with 3.6GHz 8-core Core i9: 34024 Multi-Core score
2017 iMac Pro with 3.2GHz 8-core Xeon W-2140B: 34127 Multi-Core score

NEW GPU OPTION

The top GPU option is now the AMD Radeon Pro Vega 48. Plus the Pro 580 GPU is now deemed the Pro 580X. How much faster is the Pro Vega 48? TechPowerUp has published some low level metrics that give us a clue.

Pro 580X versus Pro Vega 48
Memory Bandwidth: 217 vs 402 GB/s or
85% faster
Pixel Rate: 38.40 vs 83.20 GPixels/s or
118% faster
Texture Rate: 172.8 vs 249.6 GTexels/s or
44% faster
32 bit Floating Point: 5.530 vs 7.987 TFLOPS or
44% faster
Shading Units: 2304 vs 3072 or
33% more
Compute Units: 36 vs 48 or
32% more

Depending on how the metrics translate to real world GPU intense actions, the Pro Vega 48 should be 32% to 118% faster than the Pro 580X.

ADDENDUM: The Geekbench GPU Compute scores below for the Pro Vega 48 and Pro Vega 64 were measured in our lab. The other scores were taken from the Geekbench Browser website.

OPENCL
2019 iMac 27-inch, Pro 580X = 129057
2019 iMac 27-inch, Pro Vega 48 = 139365
2017 iMac Pro, Pro Vega 56 = 162638
2017 iMac Pro, Pro Vega 64 = 172309

METAL
2019 iMac 27-inch, Pro 580X = 116880
2019 iMac 27-inch, Pro Vega 48 = 139283
2017 iMac Pro, Pro Vega 56 = 159551
2017 iMac Pro, Pro Vega 64 = 175049

Whether those gains are worth the $450 premium is for you to decide. If you are considering the top iMac 5K model (Core i9 CPU) with 32GB of RAM and 1TB SSD, the optional Pro Vega 48 would only add 12% to the overall cost ($3799 USD versus $4249 USD).

IS THE BEST NEW IMAC 5K A BARGAIN COMPARED TO THE ENTRY LEVEL IMAC PRO?

The iMac 27 with 8-core Core i9 CPU, 32GB of RAM, 1TB SSD, and Pro Vega 48 GPU is priced at $4249 USD.

The iMac Pro with 8-core Xeon W-2140B CPU, 32GB of RAM, 1TB SSD, and Pro Vega 56 GPU is priced at $4999 USD.

Is the iMac Pro worth $750 more? Maybe.

Keep in mind that with the iMac Pro you are getting a Xeon processor, ECC memory, four TB3 ports each pair on separate controllers (versus two ports on one controller), 10Gb Ethernet (versus 1Gb Ethernet). Other superior specs include support for 4 external 4K displays (versus 2), 1080p FaceTime (versus 720p), four microphones (versus one).

The memory is user serviceable on the iMac. Upgrading memory in the iMac Pro requires an appointment with an Apple Authorized Service Provider.

NOTE: As of April 17th, we were able run and post a series of benchmarks comparing the 2019 iMac 27-inch with Core-i9 CPU and Pro Vega 48 GPU to the 2017 iMac Pro with 8-core Xeon CPU and Pro Vega 64 GPU.

Comments? Suggestions? Feel free to email me,
Follow me on Twitter @barefeats

WHERE TO BUY AMD GPUS
B&H Photo Video has the RX Vega 56 and 64.

WHERE TO BUY eGPU boxes
B&H Photo Video sells the Sonnet Breakaway 500W and 650W.
Other World Computing sells the AKiTiO Node Pro (500W)

WHERE TO BUY MEMORY UPGRADES for the 2019 iMac 27"
Trans International has iMac memory kits
Other World Computing has kits up to 64GB.

WHERE TO BUY APPLE products:
USA readers can help us earn a commission by clicking THIS TEXT LINK or on the Apple display ads at the top and on the sides this page. Then search for the product you seek.

You can also order Apple products from B&H Photo Video.

OUTSIDE USA?

Readers in Australia can support us by clicking our link to the Apple Store AU.

Readers in United Kingdom can support us by clicking our link to Apple Store UK.

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copyright 2019 Rob Art Morgan
"BARE facts on Macintosh speed FEATS"
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