Dell XPS 8700 vs. HP ProDesk 400 G6 Microtower
Comparison and Differences
Differences between Dell XPS 8700 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 Dell XPS 8700 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 HP ProDesk 400 G6 Microtower as it is running a newer generation CPU. This is not to say that Dell XPS 8700 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
The Dell XPS 8700 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 Dell XPS 8700 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 HP ProDesk 400 G6 Microtower as it has the ability to run 64 GB of RAM. The Dell XPS 8700 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 Dell XPS 8700 has 9 USB ports. The HP ProDesk 400 G6 Microtower 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. 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.
The DisplayPort is usually the more popular video port used with desktops and laptops, while the HDMI is used predominantly in consumer electronics. That's why, it is good to see that both of the models come with a DisplayPort.
The Dell XPS 8700 comes with an HDMI port, while the HP ProDesk 400 G6 Microtower 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 XPS 8700 is better equipped as it comes with 5 SATA slot(s), while the HP ProDesk 400 G6 Microtower 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 HP ProDesk 400 G6 Microtower. Sadly, the Dell XPS 8700 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 Dell XPS 8700 has a more powerful one rated at 460 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.