MikroTik CRS504 4XQ IN Model 2
MikroTik CRS504 4XQ IN Model 2

Every so often, we get a product that feels like it is breaking new ground bringing high performance to a lower power and compact footprint. This feels like one of those moments. The MikroTik CRS504-4XQ-IN is a 4-port QSFP28 switch that offers up to 4x 100GbE links at a sub $699 price point. What is more, the compact package sips power and is quiet enough that many may put it in an office without even attempting a fan swap. Although it is not perfect, this is a momentous experience for homelabs and SMB networking.

MikroTik CRS504-4XQ-IN Review Video Version

Of course, we had to have a video for this one that you can find here:

If you want to listen to the switch, see live power consumption figures, or just listen along, check this video out. As always, we recommend opening it in its own browser, tab, or app for the best viewing experience.


If you want to find the version we reviewed, you can check out the Amazon Affiliate link here.

MikroTik CRS504-4XQ-IN Hardware Overview

The switch itself is a “IN” unit which is generally for desktop units in MikroTik naming. The “-RM” is typically for rackmount units. While the CRS504-4XQ-IN is a 1U switch, the extended rack ears are optional. We showed them briefly in the video.

MikroTik CRS504 4XQ IN Front 2
MikroTik CRS504 4XQ IN Front 2

On the left, there are redundant 60W power supplies. We will get to the power consumption later, but the fact that these are only 60W should give some sense of how little power the switch uses. Also, redundant swappable power supplies in a sub $700 switch is a feature that other vendors often omit in this price range, let alone in a sub $700 100GbE switch.

MikroTik CRS504 4XQ IN Front PSUS
MikroTik CRS504 4XQ IN Front PSUS

Since this is MikroTik, there are additional power options beyond the redundant AC power supplies. The unit also sports DC power inputs.

MikroTik CRS504 4XQ IN Model Number 2
MikroTik CRS504 4XQ IN Model Number 2

Other ports on the front side are the serial console port and a management port. That 100Mbps management port also functions as a PoE-in power option. This switch not only has redundant AC power but there are two other options as well.

The big feature is, of course, the four QSFP28 ports. These QSFP28 ports are 100GbE ports, but they can also run at 40GbE speeds. They can also be broken out into 4x 25GbE links or 4x 10GbE links each. While this is a 4-port 100GbE switch, it is also a 16-port 25GbE switch.

MikroTik CRS504 4XQ IN Front Ports 2
MikroTik CRS504 4XQ IN Front Ports 2

One will probably use either QSFP28 optics, AOCs, or DACs with the switch. We expect QSFP28 to 4x SFP28 DACs to be used with these switches. For example, one could use a 100GbE link to a storage server and a workstation. Eight 25GbE ports would still be available for other nodes and servers.

MikroTik CRS504 4XQ IN With Optics Breakout AOC And Breakout DAC
MikroTik CRS504 4XQ IN With Optics Breakout AOC And Breakout DAC

As a quick aside, we know many readers will see that management port and immediately think that is a 1GbE network port. While it shows up on the default bridge in the switch, that 100M port is actually connected through the Qualcomm Atheros QCA9531L 650MHz single-core CPU. That is not fast enough to handle 100Gbps of traffic or, in a lot of cases, even 1Gbps of traffic. Instead, we suggest just using that as a management port only.

MikroTik CRS504 4XQ IN Block Diagram
MikroTik CRS504 4XQ IN Block Diagram

The switch chip is the Marvell Prestera 98DX4310. We suggest keeping all high-speed traffic on that switch chip and off of the CPU.

One side of the switch is just a metal side, but the other has a small vent. The mounting holes for the rack ears are visible on this side as well.

MikroTik CRS504 4XQ IN Side Vent
MikroTik CRS504 4XQ IN Side Vent

A reason the rear of the switch is so simple, with the second most exciting feature being a grounding nut, is because the unit is designed for dense equipment racks. Many only have cable access on the front. As a result all power and data cables are on the front of the chassis.

MikroTik CRS504 4XQ IN Rear
MikroTik CRS504 4XQ IN Rear

The biggest feature is probably the inclusion of two fans.

MikroTik CRS504 4XQ IN Rear Fans
MikroTik CRS504 4XQ IN Rear Fans

Here is what the switch looks like with the power at the top, then the Marvell and Qualcomm chips and 100GbE ports on the bottom.

MikroTik CRS504 4XQ IN Internal Overview
MikroTik CRS504 4XQ IN Internal Overview

Inside the unit are the two redundant power supplies. There is a small receiver PCB that takes power and turns the gold finger connector on the power supplies to a wired power input to the main switch board.

MikroTik CRS504 4XQ IN Internal PSU Connection
MikroTik CRS504 4XQ IN Internal PSU Connection

The main switch board has all of the ports, the Marvell switch chip, the Qualcomm Atheros CPU, memory, small amounts of storage, and then the fan outputs.

MikroTik CRS504 4XQ IN Internal Switch Board
MikroTik CRS504 4XQ IN Internal Switch Board

Here is the Marvell Prestera 98DX4310 block diagram that we found:

Marvell Prestera 98DX4310 Block Diagram
Marvell Prestera 98DX4310 Block Diagram

The Prestera chip is under the larger heat sink. On the subject of heat sinks, the QSFP28 cages have enormous heat sinks on them to cool the optical modules. Roughly half of the power consumption in the CRS504 is due to the QSFP28 modules.

MikroTik CRS504 4XQ IN Marvell Prestera Fans And QSFP28 Cages
MikroTik CRS504 4XQ IN Marvell Prestera Fans And QSFP28 Cages

Something we know that many of our readers will want to see is the fan configuration. There are two 1U 40mm fans. These are 3-pin fans. While many of our readers will see this combination and think about a Noctua fan replacement, that may not be needed here.

MikroTik CRS504 4XQ IN Marvell Prestera And Fans
MikroTik CRS504 4XQ IN Marvell Prestera And Fans

Next, let us get to the management.

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