Microsoft has quietly rolled out a second firmware update this month for Surface Pro 3. This isn't the first time Surface Pro 3 has received two separate firmware updates in a single month, which is strange enough given the device's short lifetime, but it is the first time this has happened without any warning.

The most interesting thing, since we're reaching here, is that this update is actually a firmware update. That is, it upgrades the device's UEFI firmware. Most of Microsoft's Surface "firmware" upgrades are really just driver updates.

Here's what's new in this update, which Microsoft describes as "System Firmware Update – 8/19/2014":

Surface Pro UEFI (v3.9.150.0) adds features to display BIOS password state and asset tag information, as well as improving boot times in some scenarios.

As for the history bit, Microsoft last updated the Surface Pro 3 firmware a week ago as part of its regularly scheduled Patch Tuesday updates. That update was fairly significant, improving the performance or support for a variety of devices including the Microsoft Power Cover, LifeCam and Ethernet adapter.

But it also previously updated the Surface Pro 3 firmware twice, in July, first at Patch Tuesday, and then again a few days later to fix persistent Wi-Fi issues. In that case, Microsoft had revealed that the second update was coming and even pre-announced when it would arrive.