I've been looking at the PC Engines APU line for a while. They're a line of medium size single board PCs with a DB9 serial connector and no VGA port. They also have gigabit Ethernet. Because of this they're often used as firewall machines.
I want to get one and use it as either the home router, or an experimental server to mess around with. Quite a few OpenBSD folks use them and recommend them as OpenBSD router and server hardware. They aren't too expensive, have decent specs and a small physical footprint.
One thing that's always confused me was the naming scheme, which is a little confusing at first. Initially there was the APU, then the APU2, as described on their site, which makes sense. Then the APU model numbers get a little confusing. They come in several variants, I'll list them here for context.
What do the letters between the numbers mean? What is the significance of the numbers in the first place?
Let's take the
apu3c2 as an example. The
3 here means it's version
3 of the APU board. The APU 1 is no longer sold, so it's left out of
the list on the PC Engines website, along with most of their
re-sellers. The letter
c is the revision of that board. It's pretty
much irrelevant for comparison. You'll want to get the most recent
one, as listed on the PC Engines website. The revisions are mostly
minor tweaks to the board. The final number,
2, is the number of gigabytes
of RAM (in most cases).
The APU2E2 boards have a single mSATA slot, and a regular SATA connector, two mPCIe slots, and a SIM tray. It comes with 2 external USB 3.0 type A ports, 2 internal USB 2.0 ports (header only), an SD card slot, and a GPIO header. It also has 3 Intel i211AT gigabit NICs. Using the SIM tray will remove the ability to use one of the two mPCIe slots.
So what are the major differences between version numbers? They all use the same CPU, the quad core AMD Embedded G series GX-412TC running at 1 GHz. Most other components on the boards are the same as well. I'll give a description of the differences relative to the APU2 board.
The APU2D0 is the same as the regular APU2, but without a GPIO headers, and it has only 2 NICs.
The APU3 has an extra SIM tray, and the first slot, which is mSATA only on the APU2, can be used as either an mSATA or USB 3G/LTE Modem slot. The second slot can only be used for a modem. It also lets you do GPIO tray swapping and failover, so you can use only a single modem for 2 SIMs.
The APU4D2 has 4 NICs instead of 3, and the second slot is modem only. It has 2 GB of RAM.
The APU4D4 is the same as the APU4D2, except it has dual SIM trays. It has 4 GB of RAM.
I found a lot of this information wasn't really obvious to upon first reading the PC Engines website, as there's no direct comparison between the board, and the site relies on you flipping between pages to find the details. The re-seller website I looked at also didn't elaborate on the differences.
|Board||RAM||Slot 1||Slot 2||Slot 3||Ethernet Controllers||SIM Slots||USB 2.0||Headers|
|apu2d0||2 GB||mSATA||mPCIe/Modem||mPCIe||2 i211AT||1||2||No|
|apu2e2||2 GB||mSATA||mPCIe/Modem||mPCIe||3 i211AT||1||2||Yes|
|apu2e4||4 GB||mSATA||mPCIe/Modem||mPCIe||3 i210AT||1||2||Yes|
|apu3c2||2 GB||mSATA/Modem||Modem||mPCIe||3 i211AT||2||4||Yes|
|apu3c4||4 GB||mSATA/Modem||Modem||mPCIe||3 i211AT||2||4||Yes|
|apu4d2||2 GB||mSATA||Modem||mPCIe||4 i211AT||1||2||Yes|
|apu4d4||4 GB||mSATA/Modem||Modem||mPCIe||4 i211AT||2||2||Yes|