Asus ZenPad 10 Z300C Custom ROM: Ultimate Upgrade Guide The can be given a second lease on life by installing a custom ROM, bypassing the performance issues of its outdated stock Android 5.0.2 Lollipop operating system . Released with an Intel Atom x3-C3200 processor and a modest 1GB or 2GB of RAM, the stock ZenUI skin heavily bogs down the device's speed. Installing a lightweight aftermarket firmware allows you to optimize system resources, improve battery endurance, and gain access to a cleaner, close-to-stock user interface.