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My Cloud Expert Series
At a glance
ProductWestern Digital My Cloud Expert Series (EX4100)   [Website]
SummaryFour-bay dual-core Marvell NAS with personal cloud, media serving & business features
Pros• Dual Gigabit Ethernet ports
• USB 3.0
• Remote access without port forwarding
• 10 licenses for Smartware Pro backup software
• Dual-power option
Cons• Rsync backup not supported
• Can't schedule backup to external devices

Typical Price: $350  Buy From Amazon


WD's My Cloud EX4100 is a downmarket Marvell-based version of the top-of-line Intel Atom based My Cloud DL4100 reviewed a few months ago. There's also the two-bay EX2100 we won't be reviewing, if you prefer your NASes in RAID 1 form with a slightly slower processor and half the memory.

WD sent a 16 TB WDBWZE0160KBK model as our review sample. But the EX4100 also comes in diskless (WDBWZE0000NBK), 8 TB (WDBWZE0080KBK) and 24 TB (WDBWZE0240KBK) models. As we did with the DL4100, we're showing the 0 TB BYOD model for pricing, so you can more easily compare to other BYOD NASes. WD uses the "Red" series of NAS-optimized hard drives for all diskful My Cloud SKUs.

The EX4100 and DL4100 share the case design shown in the callout graphics below, pulled from the DL4100 review.

WD My Cloud EX4100 front panel callout

WD My Cloud EX4100 front panel callout

The only difference is the EX4100 has all USB 3.0 ports vs. the DL4100's two USB 3.0 and one USB 2.0. You can get complete charts for LED status (front and rear panel) from the User Manual here. The EX4100 also uses tool-less, tray-less drive bays.

WD My Cloud EX4100 rear panel callout

WD My Cloud EX4100 rear panel callout


Table 1 shows the key components for the My Cloud EX4100, DL4100 and EX4. The dual-core Armada 388 is a big step up from the single-core Kirkwood and it shows in the performance results.

  WD My Cloud EX4100 WD My Cloud DL4100 WD My Cloud EX4
CPU Marvell dual-core Armada 388 @ 1.6 GHz Intel dual-core Atom C2338 @ 1.7 GHz Marvell Kirkwood 88F6282A1 @ 2.0 GHz (single-core)
RAM 2 GB DDR3 (Hynix H5TQ4G83AFR x4) on board
not upgradable
2 GB DDR3 (Micron MT41K256M8DA x8) on board upgradeable to 6 GB via SoDIMM DDR3 1600MHz 512 MB DDR3
Flash 512 MB Hynix H27U4G8F2DTR
512 MB Micron 29F4G08ABAEA
8 MB Winbond 25Q64FVIG
256 MB
Ethernet Marvell 88E1512 (x2) Marvell 88E1512 (x2) Marvell 88E1518-NNB2 (x2)
SATA In CPU In CPU Marvell 88SX7042
USB 3.0 Renesas D720120 Asmedia ASM1042A Etron Tech EJ168A
Table 1: Component summary comparison

The photo below shows the EX4100's board. The processor heatsink is kind of interesting. It's a hollow aluminum cube with a thermal pad taped on top for a little extra thermal mass.

WD My Cloud EX4100 PCB component side
WD My Cloud EX4100 PCB component side

The DL4100's board is shown below for comparison. What you can't see is the single SODIMM slot on the other side of the board that supports DDR3 RAM expansion up to 6 GB total. The EX series RAM is all on board and there's no expansion slot. The EX models also dispense with the buzzer, so no audio alerts. They keep the LCD front panel display, though.

WD My Cloud DL4100 PCB component side
WD My Cloud DL4100 PCB component side
Fan and drive noise was rated low. Power consumption for the external "brick" power supply was measured at 29 W (active) and 12 W (power save) with the four factory installed 4 TB WD Red (WD40EFRX) drives.


All My Cloud share a common OS, so have the same features. The only difference is supported RAID modes, which depend on the number of drive bays. I won't repeat the feature rundown provided in the DL4100 review.

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