Fujitsu Esprimo D556 vs. Fujitsu Esprimo E520
Comparison and Differences
Differences between Fujitsu Esprimo D556 and Fujitsu Esprimo E520
If you are looking for a more modern desktop, then you should go with the Fujitsu Esprimo D556 which was released in 2015. The Fujitsu Esprimo E520 is older and entered production in 2014.
Both models have the same form factor, meaning reoughtly they have the same phiysical size and form.
Processor
Usually the newer the generation of the CPU, the better the performance and efficiency is. If your budget allows it, you should go with the Fujitsu Esprimo D556 as it is running a newer generation CPU. This is not to say that Fujitsu Esprimo E520 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Fujitsu Esprimo E520 has 4 RAM slots while the Fujitsu Esprimo D556 has only 2 slot(s). This is not something to worry about. Just make sure you take it into consideration when planning how much RAM you are going to use.
The Fujitsu Esprimo D556 is using the faster 2133 MT/s RAM. The Fujitsu Esprimo E520 is slower by supporting RAM speeds of up to 1600 MT/s. In addition, you will be able to install the same amount of RAM in both models, and most probably 32 GB of RAM will be enough for most people. However, if you will be needing more RAM, make sure to check other desktop models too.
Ports
In total the Fujitsu Esprimo D556 has 10 USB ports. The Fujitsu Esprimo E520 is inferior in this regard and packs 8 USB ports. In any case, if you miss USB ports, you can always purchase a USB hub. None of the desktop models has a USB 3.1 port (10Gb/s), so if you need a fast connection to your peripherals, like external Solid State Drive, you will need to look elsewhere.
The DisplayPort is usually the more popular video port used with desktops and laptops, while the HDMI is used predominantly in consumer electronics. That's why, it is good to see that both of the models come with a DisplayPort.
None of the models has an HDMI port. If your monitor supports only the HDMI interface, you will need to buy an adapter. Such adapters are cheap so nothing to worry about.
SATA ports are placed on the system board and it is where you connect your HDD, SSD and Optical Disk Drives. More SATA slots will allow you to have more drives running at the same time. In this regard the Fujitsu Esprimo E520 is better equipped as it comes with 4 SATA slot(s), while the Fujitsu Esprimo D556 has 3 slot(s).
If you want the fastest transfer speeds for your SSD, an M.2 interface is crucial. Thus, if the M.2 SSD slot is a mandatory requirement for you, go with the Fujitsu Esprimo D556. Sadly, the Fujitsu Esprimo E520 has no such slot, and you will be forced to use the SATA interface instead.
Make sure that the available M.2 slot supports the PCIe (also called NVMe) interface. This is important as there are M.2 slots which support only the inferior SATA III interface. For comparison, the SATA III interface has max speeds of 6Gb/s, while the PCIe 3.0 x4 will support speeds up to 32Gb/s!
Power Supply
Looking at the Power Supply Unit (PSU) of the two models we don't see any differences. For either of them you get a maximum power of 280 Watts. However be careful, many models have more than one power supply option. When buying your computer, it is a good idea to get a version with the most powerful PSU. This will potentially allow you to upgrade to a more powerful GPU for example.
Motherboard
