Some OEM vendors (HP, Dell, Compaq) lock this setting. If the BIOS detects a discrete card, it hides the UMA option. Solution: Remove the discrete GPU physically. Reboot and enter BIOS again. The UMA option should appear.
At first glance, moving from Discrete (DIS) to Unified Memory (UMA) seems like a downgrade. Why would anyone do it? Common scenarios include:
) are available on repair repositories like Scribd and CTLAB .
Switching to UMA is not always seamless. Here are the most common issues and solutions.