> Viską surinkau, įdiegiau Windows 10 į Samsung SSD ir diegimo metu Windows 10 man suskaidė WD HDD į tris dalis. Ir GPT neleidžia 
> daryti, tas pasirinkimas neaktyvus atsidarius Disk managment. Netiki - galiu skreen shot atsiųsti.

http://www.disk-partition.com/gpt-mbr/convert-to-gpt-grayed-out-0528.html
https://social.technet.microsoft.com/Forums/en-US/3007346f-cf7b-4089-9628-36d394da8240/convert-mbr-to-gpt

By default, if MBR disk has disk partitions, the convert to GPT is gray.
You can change a disk from MBR to GPT as long as the disk does not contain any partitions or volumes.

T.y. atsidarius Disk managment istrink visas sukurtas particijas, tada turetu konvertuotis.