You might have the legacy boot option set in the BIOS: If you are accelerating the system disk (OS Installed) proceed with details below. Right Click on left panel for the Disk being checked (for example Disk 0, Disk 1, etc) > Properties > Volumes. Open Disk Management by pressing Windows key + R > select Disk Management.If the drive is a secondary/data drive (no OS installed), you can use third-party applications such as EaseUS* to convert from MBR to GPT. If you have the legacy boot option set in the BIOS (Basic Input/Output System), it's possible the drive partition table is Master Boot Record (MBR). This article describes methods to convert SSDs from MBR (Master Boot Record) to GPT (GUID Partition Table) partition structure. We don't offer support for third-party tools. We don't endorse the content, products, or services offered. Links provided to third-party tools and sites are for your convenience.Before proceeding, we recommend backing up all data.