Dell OptiPlex 980 DT vs. Dell Vostro 3900
Comparison and Differences
Differences between Dell OptiPlex 980 DT and Dell Vostro 3900
If you are looking for a more modern desktop, then you should go with the Dell Vostro 3900 which was released in 2014. The Dell OptiPlex 980 DT is older and entered production in 2010.
If you are looking for the smaller form factor the Dell OptiPlex 980 DT is the right one for you. It is smaller than the Dell Vostro 3900 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 Dell Vostro 3900 as it is running a newer generation CPU. This is not to say that Dell OptiPlex 980 DT is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Dell OptiPlex 980 DT has 4 RAM slots while the Dell Vostro 3900 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 Dell Vostro 3900 is using the faster 1600 MT/s RAM. The Dell OptiPlex 980 DT is slower by supporting RAM speeds of up to 1333 MT/s. In addition, you will be able to install the same amount of RAM in both models, and most probably 16 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
Both models have the same amount of USB ports for total count of 8. If this is not enough, using a USB hub is always a viable option. 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 Dell OptiPlex 980 DT has a DisplayPort. The Dell Vostro 3900 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 Vostro 3900 comes with an HDMI port, while the Dell OptiPlex 980 DT 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 slots are located on the motherboard and it is where SSD, HDD and Optical Disk Drives are connected. Each of the two models being compared have 4 SATA slot(s). Keep in mind that having too few SATA slots might limit your options for connecting additional memory drives.
M.2 SSD interface allows you to transfer data with higher speeds compared to the old SATA interface. Unfortunately, neither the Dell OptiPlex 980 DT, nor the Dell Vostro 3900 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 980 DT comes with a decent 255 Watt PSU, but the Dell Vostro 3900 has a more powerful one rated at 300 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
