All our images are digitally signed and therefore it's possible to check theirs authentication. You need to unzip the download package and issue those commands (Linux):
**Important note:** Make sure you use a **good & reliable** SD card. If you encounter boot or stability troubles in over 95 percent of the time it's either insufficient power supply or related to SD card (bad card, bad card reader, something went wrong when burning the image). Armbian can simply not run on unreliable hardware so checking your SD card with either [F3](http://oss.digirati.com.br/f3/) or [H2testw](http://www.heise.de/download/h2testw.html) is mandatory if you run in problems. Since [counterfeit SD cards](http://www.happybison.com/reviews/how-to-check-and-spot-fake-micro-sd-card-8/) are still an issue checking with F3/H2testw directly after purchase is **highly recommended**.
7z and zip archives can be uncompressed with [7-Zip](http://www.7-zip.org/) on Windows, [Keka](http://www.kekaosx.com/en/) on OS X and 7z on Linux (apt-get install p7zip-full). Raw images can be written with [Etcher](https://www.etcher.io) (all OS):
Also important: SD cards are optimised for sequential reads/writes as it's common in digital cameras. This is what the *speed class* is about. And while you shouldn't buy or use any card rated less than *class 10* you should especially take care to choose one that is known to show high random I/O performance since this is way more performance relevant when used with any SBC. Even cards advertised as being 'high speed' can show horribly low random IO performance in reality.
- [SD card performance with Armbian - Thomas Kaiser](http://forum.armbian.com/index.php/topic/954-sd-card-performance/)
- [Raspberry Pi microSD card performance comparison - Jeff Geerling](http://www.jeffgeerling.com/blogs/jeff-geerling/raspberry-pi-microsd-card)
- [The Best microSD Card - Kimber Streams](http://thewirecutter.com/reviews/best-microsd-card/)
# How to boot?
Insert SD card into a slot and power the board. First boot takes around 3 minutes then it reboots and you will need to wait another one minute to login. This delay is because system updates package list and creates 128Mb emergency SWAP on the SD card.
Normal boot (with DHCP) takes up to 35 seconds with a class 6 SD CARD and cheapest board.
# How to login?
Login as **root** on console or via SSH and use password **1234**. You will be prompted to change this password at first login. You will then be asked to create a normal user account that is sudo enabled (beware of default QWERTY keyboard settings at this stage).
Desktop images starts into desktop without asking for password. To change this add some display manager:
This will not only update distribution packages (Debian/Ubuntu) but also updates Armbian kernel, u-boot and board support package if available. So if you've seen in the list of updated packages the names _u-boot_ or _linux_ the following command is required for changes to take effect:
On Allwinner devices after switching to boot from NAND or eMMC clearing the boot loader signature on the SD card is recommended: `dd if=/dev/zero of=/dev/mmcblkN bs=1024 seek=8 count=1` (replace `/dev/mmcblkN` with the correct device node -- in case you run this directly after `nand-sata-install` without a reboot in between then it's `/dev/mmcblk0`). When booting from eMMC to get SD cards auto-detected on Allwinner legacy images please consider changing `mmc0`'s `sdc_detmode` from 3 to 1 in the board's fex file (see [here](http://forum.armbian.com/index.php/topic/1702-orange-pi-plus-2e-where-is-16ghz-and-sd/?p=13163) for details).
