How to Enable Intel® Optane™ Memory If BIOS Is Set to Legacy Mode

• Unable to change the SATA Mode Selection to RST; the system does not boot after that.
• Operating System (OS) will not boot after changing the BIOS mode to Intel® RST Premium with Intel® Optane™ System Acceleration (RAID)

BIOS set in Legacy Mode means that the partition style of the OS drive is set in MBR format which is not compatible with Intel® Optane™ memory. When the SATA controller mode in BIOS is changed to Intel® RST Premium with Intel® Optane™ System Acceleration (RAID) without converting the partition style, the system will have booting issues. In order to convert the partition style from MBR to GPT follow these steps: 

1. Back up all files on your system
2. Convert the partition table from MBR to GPT using the Windows* tool MBR2GPT.exe. Make sure that you have the latest Windows® updates installed. 
   1. Open Command Prompt with administrator privileges
   2. Issue the following command: mbr2gpt.exe /convert /allowfullOS
3. When the process is complete, restart the system and go into BIOS.
4. Within BIOS, set the SATA Mode Selection to Intel RST Premium with Intel® Optane™ System Acceleration (RAID). Note: The BIOS options may vary by vendor, below are suggested steps that may apply to your system BIOS. For specific BIOS navigation options, contact the system manufacturer.
   1. Within BIOS, press F7 to go to the Advanced Mode. 
   2. Go to Boot\CMS (Compatibility Support Module) and disable this option 
   3. Go to Advanced\PCH Storage Configuration and set the SATA Mode setting to Intel RST Premium with Intel® Optane™ System Acceleration (RAID)
   4. Press F10 to save changes and restart the system 

The system should be able to boot now into the OS after the BIOS changes. Continue with the enablement process of the Intel® Optane™ memory from the OS.