Dell OptiPlex 390 DT vs. Fujitsu Esprimo P920
Comparison and Differences
Differences between Dell OptiPlex 390 DT and Fujitsu Esprimo P920
If you are looking for a more modern desktop, then you should go with the Fujitsu Esprimo P920 which was released in 2014. The Dell OptiPlex 390 DT is older and entered production in 2011.
If you are looking for the smaller form factor the Dell OptiPlex 390 DT is the right one for you. It is smaller than the Fujitsu Esprimo P920 and will fit more easily under your desk.
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 P920 as it is running a newer generation CPU. This is not to say that Dell OptiPlex 390 DT is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Fujitsu Esprimo P920 has 4 RAM slots while the Dell OptiPlex 390 DT 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 P920 is using the faster 1600 MT/s RAM. The Dell OptiPlex 390 DT is slower by supporting RAM speeds of up to 1333 MT/s. Additionally, if you will be needing a lot of RAM, better go for the Fujitsu Esprimo P920 as it has the ability to run 32 GB of RAM. The Dell OptiPlex 390 DT can do a bit less at max 8 GB. Most of the times, this should be sufficient for the majority of users.
Ports
In total the Fujitsu Esprimo P920 has 12 USB ports. The Dell OptiPlex 390 DT 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.
Unfortunately, only the Fujitsu Esprimo P920 has a DisplayPort. The Dell OptiPlex 390 DT does not have one? Don't worry though, nowadays video adapters are cheap and you can get almost any combination of conversion types.
The Dell OptiPlex 390 DT comes with an HDMI port, while the Fujitsu Esprimo P920 does not support the interface. Of course missing HDMI port is something that can be easily fixed with a good adapter (e.g. DisplayPort to HDMI).
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 P920 is better equipped as it comes with 6 SATA slot(s), while the Dell OptiPlex 390 DT has 4 slot(s).
M.2 SSD interface allows you to transfer data with higher speeds compared to the old SATA interface. Unfortunately, neither the Dell OptiPlex 390 DT, nor the Fujitsu Esprimo P920 has one. However, you can still use a SATA SSD drive which should give you satisfactory performance.
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
Having a Power Supply Unit with high power rating is important, if you are going to use components which require extra power. The Dell OptiPlex 390 DT comes with a decent 250 Watt PSU, but the Fujitsu Esprimo P920 has a more powerful one rated at 280 Watts. Choosing either one depends on your specific requirements and use case. Also don't forget that some models might have more than one PSU option - try to always get the most powerful one, especially if you plan to upgrade to a powerful GPU.
Motherboard
