The Pine A64 is a powerful and cheap (just $15) single-board computer that can be used for anything most SBCs are used nowadays.
SpecsUpdate
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Pros
Pro Can stream 4K video
The Pine64 has a HDMI port which offers 4K streaming capabilities and coupled with support for Kodi it can be transformed into a pretty powerful media streaming centre.
Pro Extremely powerful for its price
With a price of $15 it's one of the most powerful and fast single board computers on the market today, able to compete with products that are more than double its price.
Pro Optional and bespoke 7" Touchscreen and Analog Audio DAC
Range of accessories now available that expand core functionality without worrying [too much] about compatibility.
Pro Additional GPIOs (Euler bus)
A GPIO (general purpose input/output) port is included, which allows for more flexible use.
Pro Versatile hardware
The board already comes with a lot of things.
Cons
Con Bad support
Con Finicky PSU support
It's very hard to find a PSU (power supply unit) that works with Pine64. While other single board computers (such as the ODROID, MK802IV, and MK808) work with virtually any 5V/2A PSUs, the power supply is a bit too sensitive (even when using a power strip with 8 USB ports with all SoCs running off the 1A or 2.4A connections).
Con No onboard Wi-Fi or Bluetooth
Not included by default, but an optional WiFi 802.11 b/g/n & Bluetooth module can be added.
Con Huge size
The A64 is 127mm x 79mm which is significantly larger than other single board computers on the market.
Con You can't use an adapter to DVI VGA
It only supports HDMI.