Alienware X51 R3 vs. Dell OptiPlex 3090 M

Differences between Alienware X51 R3 and Dell OptiPlex 3090 M

If you are looking for a more modern desktop, then you should go with the Dell OptiPlex 3090 M which was released in 2021. The Alienware X51 R3 is older and entered production in 2015.

If you are looking for the smaller form factor the Dell OptiPlex 3090 M is the right one for you. It is smaller than the Alienware X51 R3 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 OptiPlex 3090 M as it is running a newer generation CPU. This is not to say that Alienware X51 R3 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 Dell OptiPlex 3090 M is using the faster 2933 MT/s RAM. The Alienware X51 R3 is slower by supporting RAM speeds of up to 2133 MT/s. Additionally, if you will be needing a lot of RAM, better go for the Dell OptiPlex 3090 M as it has the ability to run 64 GB of RAM. The Alienware X51 R3 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 Alienware X51 R3 has 8 USB ports. The Dell OptiPlex 3090 M 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. 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 Dell OptiPlex 3090 M 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.

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.

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 Alienware X51 R3 is better equipped as it comes with 3 SATA slot(s), while the Dell OptiPlex 3090 M has 1 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 3090 M. Sadly, the Alienware X51 R3 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 3090 M comes with a decent 65 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.

Motherboard