wow, System update took a long time here. Had the screen with "System update is being installed" for 5 minutes. Then fan suddenly really loud and sp3 shut down. Made sp3 on again, another update. It restarted itself again. Now all is installed sucessful.
so dont get nervous
The following updates will be listed as “System Firmware Update – 9/9/2014” within the Windows Update History.
Surface Pro UEFI update (v 3.10.250.0) improves system experience and enhances overall system stability, including Wi-Fi.
Surface Pro Embedded Controller Firmware update (v 38.6.50.0) enhanced support for system performance and user experience, including thermostat icon on boot.
Surface Pro System Aggregator Firmware update (v 3.9.350.0) increases the overall system reliability and compatibility with a Surface cover.
Surface Integration driver update (v 2.0.1102.0) enhances user experience, including Wi-Fi stability.
Surface Wi-Fi and Bluetooth driver update (v 15.68.3055.107) improves Wi-Fi/ Bluetooth reliability and system stability, and significantly enhances the user experience.
Note When Surface updates are provided via the Windows Update service, they are delivered in stages to Surface customers. As a result, not every Surface will receive the update at the same time, but the update will be delivered to all devices. If you have not received the update then please manually check Windows Update later.