so i got this old pc with non-uefi mobo used as a data server on home network. and i have this gpt hdd that i want to use as a data-only storage on this system. would there be any compatibility issues?
Can Windows XP x64 read, write, and boot from GPT disks? Windows XP x64 Edition can use GPT disks for data only. Can the 32-bit version of Windows XP read, write, and boot from GPT disks? No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software. Can Windows Vista, Windows Server 2008, and later read, write, and boot from GPT disks? Yes, all versions can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on UEFI-based systems. https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-and-gpt-faq
Assuming you have Windows 7 onwards installed, I see no possible compatibility issues. Also you want to format the disk using NTFS.
@Brian K hi brian i assume you're asking this because of the 2tb limit on non-uefi systems, right? it's only 1tb.
You can convert a GPT disk to MBR. Or vice versa. As many times as you like. It's a matter of preference. If you like a GPT disk, fine. But if you would prefer a MBR disk, convert it.
@Brian K thank you. just to make sure, the data will be intact if the disk is converted, right? and are there any other advantages of gpt over mbr other than 2tb limit, higher resilliance to corruption, and number of partitions allowed?
I use BootIt for the conversions and the data is preserved. You can't use Diskpart unless the disk has no partitions. I prefer MBR disks in MBR systems and GPT disks in GPT/UEFI systems. But that's not hard and fast. Use whichever you prefer.