What's the difference between APU2, APU3 and APU4 boards?

Post last updated on 2020-10-11

APU2, APU3 and APU4 boards are very similar in design and performance. There are few differences that are worth knowing if you plan to build a system based on APU motherboard.

You can connect only one WiFi module to APU3/APU4 boards, while you can connect two WiFi modules to APU2 board. This means that you can build a 2.4Ghz + 5Ghz Access point on APU2, but not on APU3/APU4.

APU3 can be seen as a variant of APU2 optimized for LTE. See /knowledge-base/apu-boards-spec-comparison for the full comparison.

APU3/APU4 boards have two SIM slots, and are optimized for LTE connectivity. It means that you can connect two mPCIe LTE modems and have 2 additional links for failover or as a main connection. Even if you are just planning on having one LTE/3G connection, we recommend APU3 or APU4 as these board have been extensively tested by PC Engines and optimized for this purpose.

The only difference between APU3 and APU4 is in number of LAN ports. APU4 has 4 ports while APU3 has 3.

APU2x4 has i210AT network interfaces (4 receiving/sending queues), while APU2x2, APU3 and APU4 have i211AT (2 sending/receiving queues). While APU2x4 has a more performant network interface, in practice I have not seen a noticeable advantage.

Routing/Networking performance of APU2, APU3, and APU4 don't differ in a noticeable way. All boards handle regular networking very well.

There are two typical uses for APU3/APU4 boards:

one main connection via cable NIC and a second, failover connection via LTE modem (for critical systems that must always be online)
single LTE connection serving as a main gateway. (for remote locations that don't have cable broadband connectivity)

Power consumption is very similar - about 6W.