The 2017 iMac 5K PCie flash storage versus other recent Macs
August 18th, 2017, by rob-ART morgan, mad scientist
Updated August 21st with 2017 rMBP results
How does the 2017 iMac 5K's internal PCIe based flash storage speed compare to the previous iMac 5K and to the latest Retina MacBook Pro?
GRAPH LEGEND
2017 rMBP - '2017' Retina MacBook Pro 13-inch, 3.5GHz Dual-Core i7-7567U (Turbo Boost to 4.0GHz), 16G of 2133MHz LPDDR3 memory, Intel Iris Plus Graphics 650, 1TB PCIe based internal flash storage
2017 iMac 5K - '2017' iMac 5K with 3.8GHz Quad-Core i5, 64G of 2400MHz DDR4 memory, Radeon Pro 580 GPU (8GB VRAM), 1TB PCIe based internal flash storage
2016 rMBP - 'late 2016' Retina MacBook Pro 15-inch, 2.9GHz Quad-Core i7-6920HQ (Turbo Boost to 3.8GHz), 16G of 2133MHz LPDDR3 memory, AMD Radeon Pro 460 (4G), 1TB PCIe based internal flash storage
2015 iMac 5K - 'late 2015' iMac 5K with 4GHz Quad-Core i7, 64G of 1867MHz DDR3 memory, Radeon R9 M395X GPU (4GB VRAM), 1TB PCIe based internal flash storage
OLD MAC VERSUS NEW
AJA System Test used a 16GB Test Size, 3840x2160 4K RED HD resolution, and 16bit RGB Codec
(HIGHER megabytes per second = FASTER)
STORAGE DEVICES COMPARED
GRAPH LEGEND
Internal Flash - 1TB PCIe based internal flash storage of '2017' iMac 5K
Thunder3*2 Flash*4 - Dual Thunderbolt 3 expansion boxes each with an Amfeltec PCIe Gen3 M.2 Carrier and dual Samsung SM951 512G flash blades mounted; all four striped with SoftRAID 5.6.1 connected to separate Thunderbolt 3 (USB-C) ports of '2017' iMac 5K
Thunder3 Flash*2 - Thunderbolt 3 expansion box with Amfeltec PCIe Gen3 M.2 Carrier with dual Samsung SM951 512G flash blades mounted and striped with SoftRAID 5.6.1 connected to Thunderbolt 3 (USB-C) port of '2017' iMac 5K
USB 3.1 G2 Flash*2 - SanDisk Extreme 900 USB 3.1 Gen 2 Portable SSD connected to USB-C port of '2017' iMac 5K
USB3 Flash*2 - SanDisk Extreme 900 USB 3.1 Gen 2 Portable SSD connected to USB-A port of '2017' iMac 5K
AJA System Test used a 16GB Test Size, 3840x2160 4K RED HD resolution, and 16bit RGB Codec
(HIGHER AVERAGE megabytes per second = FASTER)
WHAT DID WE LEARN?
With NVMe flash storage running with x4 Link Width and 8GT/s Link Speed, the 2017 iMac 5K's PCIe based flash storage can almost match the speed of the 2017 Retina MacBook Pro's flash storage.
What about the Fusion drive? We benchmarked the 2GB version. If transfer size is less that the free space of the 'fused' flash module, it can match the READ speed of the pure flash storage but the write speed was only one-third as fast.
Thunderbolt 3 transfer speeds matched the MacBook Pros as well. Note that connecting two Thunderbolt 3 fast storage devices to separate Thunderbolt 3 ports and striping them does not double the transfer speed. That's because they share the same bus.
We confirmed that the USB-C port of the 2017 iMac 5K transfers at twice the speed of the USB-A port - as expected. However it takes a striped flash enclosure like the SanDisk Extreme 900 to squeeze out the maximum USB 3.1 Gen 2 speed.
BTW, the Extreme 900 is currently the fastest bus-powered storage device you can buy. The previous bus-powered speed 'champ' was the Sonnet Fusion PCIe Thunderbolt 2 Flash Drive which is no longer available. However, Sonnet will soon be shipping the Fusion Thunderbolt 3 PCIe Flash Drive which will surely be the fastest bus-powered storage device regardless of the interface.
