HP DL380e Gen8 not support the UEFI mode, you can find the option in HP Gen 9.
we can say that UEFI boot mode support more than 2 TB storage and Legacy mode support UP to 2 TB, so the solution is below:
For Example:
1. if you have storage 10TB, so create the two raid ( one for window and 2nd for storage )
2. when you choose the partition for windows so make sure there is no any extra partition without these raid.
3. install the window in window raid partition
4. complete the startup setup
5. so when you go to Disk management so there you will see the 2 disk online
one is Raid for storage
second is raid for windows
6. so delete the partition from the disk management of the storage RAID.
7. right click on Disk online > convert to GPT
NOTE:
its only done when there is no any Partition allocate or system reserved space. and i am sure it ll work because it was tested by my hand after spend days.
for more details you can email me: usman@hmea.com