Dell OptiPlex 390 MT vs. Lenovo ThinkCentre M900 Small
Comparison and Differences
Differences between Dell OptiPlex 390 MT and Lenovo ThinkCentre M900 Small
If you are looking for a more modern desktop, then you should go with the Lenovo ThinkCentre M900 Small which was released in 2015. The Dell OptiPlex 390 MT is older and entered production in 2011.
If you are looking for the smaller form factor the Lenovo ThinkCentre M900 Small is the right one for you. It is smaller than the Dell OptiPlex 390 MT 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 Lenovo ThinkCentre M900 Small as it is running a newer generation CPU. This is not to say that Dell OptiPlex 390 MT is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Lenovo ThinkCentre M900 Small has 4 RAM slots while the Dell OptiPlex 390 MT 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 Lenovo ThinkCentre M900 Small is using the faster 2133 MT/s RAM. The Dell OptiPlex 390 MT 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 Lenovo ThinkCentre M900 Small as it has the ability to run 64 GB of RAM. The Dell OptiPlex 390 MT can do a bit less at max 8 GB. Most of the times, this should be sufficient for the majority of users.
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 Lenovo ThinkCentre M900 Small has a DisplayPort. The Dell OptiPlex 390 MT 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 MT comes with an HDMI port, while the Lenovo ThinkCentre M900 Small 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 Dell OptiPlex 390 MT is better equipped as it comes with 4 SATA slot(s), while the Lenovo ThinkCentre M900 Small has 3 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 MT, nor the Lenovo ThinkCentre M900 Small 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 Lenovo ThinkCentre M900 Small comes with a decent 210 Watt PSU, but the Dell OptiPlex 390 MT has a more powerful one rated at 265 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
