Alienware Aurora R4 vs. HP ProDesk 400 G6 Microtower
Comparison and Differences
Differences between Alienware Aurora R4 and HP ProDesk 400 G6 Microtower
If you are looking for a more modern desktop, then you should go with the HP ProDesk 400 G6 Microtower which was released in 2018. The Alienware Aurora R4 is older and entered production in 2012.
If you are looking for the smaller form factor the Alienware Aurora R4 is the right one for you. It is smaller than the HP ProDesk 400 G6 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 HP ProDesk 400 G6 Microtower as it is running a newer generation CPU. This is not to say that Alienware Aurora R4 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Alienware Aurora R4 has 4 RAM slots while the HP ProDesk 400 G6 Microtower 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 HP ProDesk 400 G6 Microtower is using the faster 2666 MT/s RAM. The Alienware Aurora R4 is slower by supporting RAM speeds of up to 1866 MT/s. Additionally, if you will be needing a lot of RAM, better go for the HP ProDesk 400 G6 Microtower as it has the ability to run 64 GB of RAM. The Alienware Aurora R4 can do a bit less at max 32 GB. Most of the times, this should be sufficient for the majority of users.
Ports
In total the HP ProDesk 400 G6 Microtower has 8 USB ports. The Alienware Aurora R4 is inferior in this regard and packs 5 USB ports. In any case, if you miss USB ports, you can always purchase a USB hub. 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 HP ProDesk 400 G6 Microtower has a DisplayPort. The Alienware Aurora R4 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 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 3 SATA slot(s). Keep in mind that having too few SATA slots might limit your options for connecting additional memory drives.
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 HP ProDesk 400 G6 Microtower. Sadly, the Alienware Aurora R4 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 HP ProDesk 400 G6 Microtower comes with a decent 310 Watt PSU, but the Alienware Aurora R4 has a more powerful one rated at 875 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.