Alienware X51 R3 vs. HP ProDesk 480 G1 Microtower
Comparison and Differences
Differences between Alienware X51 R3 and HP ProDesk 480 G1 Microtower
If you are looking for a more modern desktop, then you should go with the Alienware X51 R3 which was released in 2015. The HP ProDesk 480 G1 Microtower is older and entered production in 2013.
If you are looking for the smaller form factor the Alienware X51 R3 is the right one for you. It is smaller than the HP ProDesk 480 G1 Microtower 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 Alienware X51 R3 as it is running a newer generation CPU. This is not to say that HP ProDesk 480 G1 Microtower is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
Both models have have equal amount of ram slots (2 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 Alienware X51 R3 is using the faster 2133 MT/s RAM. The HP ProDesk 480 G1 Microtower 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 Alienware X51 R3 as it has the ability to run 32 GB of RAM. The HP ProDesk 480 G1 Microtower can do a bit less at max 16 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. What is nice about the Alienware X51 R3, is that it has 2 USB 3.1 port(s) which allows transfer of up to 10Gb/s. Unfortunately, the HP ProDesk 480 G1 Microtower 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.
Unfortunately, only the Alienware X51 R3 has a DisplayPort. The HP ProDesk 480 G1 Microtower does not have one? Don't worry though, nowadays video adapters are cheap and you can get almost any combination of conversion types.
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 HP ProDesk 480 G1 Microtower is better equipped as it comes with 4 SATA slot(s), while the Alienware X51 R3 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 Alienware X51 R3, nor the HP ProDesk 480 G1 Microtower 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 HP ProDesk 480 G1 Microtower comes with a decent 300 Watt PSU, but the Alienware X51 R3 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.