Alienware Aurora R5 vs. Dell XPS 8940
Comparison and Differences
Differences between Alienware Aurora R5 and Dell XPS 8940
If you are looking for a more modern desktop, then you should go with the Dell XPS 8940 which was released in 2020. The Alienware Aurora R5 is older and entered production in 2015.
If you are looking for the smaller form factor the Alienware Aurora R5 is the right one for you. It is smaller than the Dell XPS 8940 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 XPS 8940 as it is running a newer generation CPU. This is not to say that Alienware Aurora R5 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
Both models have have equal amount of ram slots (4 RAM). Usually two RAM slots are more than enough for most cases. However, the count should be taken into account when planning how much and what combination of RAM you are going to need for your system.
The Dell XPS 8940 is using the faster 2666 MT/s RAM. The Alienware Aurora R5 is slower by supporting RAM speeds of up to 2400 MT/s. Additionally, if you will be needing a lot of RAM, better go for the Dell XPS 8940 as it has the ability to run 128 GB of RAM. The Alienware Aurora R5 can do a bit less at max 64 GB. Most of the times, this should be sufficient for the majority of users.
Ports
In total the Alienware Aurora R5 has 13 USB ports. The Dell XPS 8940 is inferior in this regard and packs 10 USB ports. In any case, if you miss USB ports, you can always purchase a USB hub. It's great that both of the models have USB 3.1 ports which will allow you to exchange data with your peripherals at up to 10Gb/s. But if you need maximum connectivity, go with the Alienware Aurora R5 as it has 2 USB3.1 ports (the Dell XPS 8940 has 1).
Unfortunately, only the Dell XPS 8940 has a DisplayPort. The Alienware Aurora R5 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 XPS 8940 comes with an HDMI port, while the Alienware Aurora R5 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 Alienware Aurora R5 is better equipped as it comes with 4 SATA slot(s), while the Dell XPS 8940 has 3 slot(s).
When your goal is to have the fastest SSD transfer speeds, an M.2 interface is crucial. Thus, it is good that both models have M.2 SSD slots. Today M.2 SSDs are not much more expensive than the average SATA drives, so it really does not make sense to invest in SATA drives anymore.
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 XPS 8940 comes with a decent 500 Watt PSU, but the Alienware Aurora R5 has a more powerful one rated at 850 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.