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.
APU2
APU2 image showing one SIM slot.
Not recommended for 3G/LTE connectivity.
Possibility to connect 2x WiFi modules
Intel I210-AT Ethernet Controllers
APU3
APU3 image showing two SIM slots (upper right corner).
Optimized for 3G/LTE connectivity
Possibility to connect 2x 3G/LTE modems
Possibility to connect 1x WiFi module
Intel I211-AT Ethernet Controllers
APU4
APU4 is almost the same as APU3, but has 4 NICs instead of 3
Optimized for 3G/LTE connectivity
Possibility to connect 2x 3G/LTE modems
Possibility to connect 1x WiFi module
Intel I211-AT Ethernet Controllers
APU2B, APU2C, APU2D, APU2E
| Slot | Interfaces | Use Cases |
|---|---|---|
| J14 (mPCIe1) | USB, PCIe, SIM | LTE and Wifi modules |
| J13 (mPCIe2) | USB, PCIe SIM | LTE and Wifi modules |
| J12 (mSATA) | mSATA | only mSATA disks |
APU3A, APU3B, APU3C
| Slot | Interfaces | Use Cases |
|---|---|---|
| J16 (mPCIe1) | USB, PCIe | USB and Wifi modules |
| J15 (mPCIe2) | USB, SIM1 | only LTE modules |
| J14 (mSATA) | mSATA, USB, SIM2 | mSATA disks and LTE modules |
APU4A, APU4B, APU4C, APU4D
| Slot | Interfaces | Use Cases |
|---|---|---|
| J15 (mPCIe1) | USB, PCIe | USB and Wifi modules |
| J14 (mPCIe2) | USB, SIM1 | only LTE modules |
| J13 (mSATA) | mSATA, USB, SIM2 | mSATA disks and LTE modules |
LTE / 4G compatibility
It's important to note that APU boards don't have built-in LTE/3G modems. Modems must be purchased separately and connected to the mPCIe slots.
There are several modems that have been tested and are known to work well with APU3 and APU4. The ones we have tested are:
- HUAWEI ME909u-521.
- HUAWEI ME909u-120.
- Quectel EC25-E
Tip: check out many similar articles in our Knowledge Base.
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