Alienware X51 R2 vs. Dell OptiPlex 5090 SFF
Comparison and Differences
Differences between Alienware X51 R2 and Dell OptiPlex 5090 SFF
If you are looking for a more modern desktop, then you should go with the Dell OptiPlex 5090 SFF which was released in 2021. The Alienware X51 R2 is older and entered production in 2013.
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 Dell OptiPlex 5090 SFF as it is running a newer generation CPU. This is not to say that Alienware X51 R2 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Dell OptiPlex 5090 SFF has 4 RAM slots while the Alienware X51 R2 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 OptiPlex 5090 SFF is using the faster 3200 MT/s RAM. The Alienware X51 R2 is slower by supporting RAM speeds of up to 1600 MT/s. Additionally, if you will be needing a lot of RAM, better go for the Dell OptiPlex 5090 SFF as it has the ability to run 128 GB of RAM. The Alienware X51 R2 can do a bit less at max 16 GB. Most of the times, this should be sufficient for the majority of users.
Ports
In total the Dell OptiPlex 5090 SFF has 10 USB ports. The Alienware X51 R2 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. What is nice about the Dell OptiPlex 5090 SFF, is that it has 1 USB 3.1 port(s) which allows transfer of up to 10Gb/s. Unfortunately, the Alienware X51 R2 has no such port, thus restricting your transfer speeds significantly. For people who want to use external drives on regular basis, this might be an issue.
DisplayPort is crucial for any desktop machine. It is good to see that both models are featuring DisplayPorts. However, the Dell OptiPlex 5090 SFF comes with 2 ports, while the Alienware X51 R2 has only 1. If you are planning to use multiple monitors, the Dell OptiPlex 5090 SFF is the better choice.
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 Dell OptiPlex 5090 SFF is better equipped as it comes with 4 SATA slot(s), while the Alienware X51 R2 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 Dell OptiPlex 5090 SFF. Sadly, the Alienware X51 R2 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
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 5090 SFF comes with a decent 300 Watt PSU, but the Alienware X51 R2 has a more powerful one rated at 330 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
