Asus H170M-Plus Raid Problems

So here is my new PC with following configuration.

Asus H170M-Plus Motherboard
Core i5 6402P Processor
8 GB DDR4 Ram
1 TB Seagate Barracuda + 1 TB Seagate Barracuda

I wish to setup RAID 1(Mirroring).

Problems :

1. Under EZsetup utility, i click, RAID, then it restarts and asks for PCI/SATA raid.
2. I select SATA and click next, and then i can see only 1 drive in it.
3. Then i cant click next, i go to advanced options, Intel RST and the other drive is listed as Non-Raid drive. I have switched it in various ports and even interchanged them but any 1 drive is listed as non raid.
4. Switch to legacy OPROM(everything legacy), select RAID under sata configuration, restart.
5. I cannot access Intel RST by pressing Ctrl+I.

All latest drivers for RAID are installed with BIOS of May 2016. Kindly suggest.

Hard disks are ok and work fine under AHCI mode.

Thank You

@siren :
Welcome at Win-RAID Forum!

If you want to create an Intel RAID Array in UEFI mode, I recommend to do the following:
1. Enter the BIOS and choose the "DEFAULT" settings for everything.
2. Go to "Advanced Options" > "Storage Configuration" > "SATA Mode Selection" and set it to "RAID".
3. Save the new BIOS settings and power off the computer completely for a minute.
4. Turn on the computer, enter the BIOS and search for the new/added option "Intel(R) Rapid Storage Technology" (it probably will be within the "Storage Configuration" section).
5. Enter the "Intel(R) Rapid Storage Technology" option and create the RAID Array according your wishes.
6. Save the new BIOS settings and reboot.
7. Enter the BIOS again, go to the "Advanced Options" > "BOOT" section and choose your favoured Boot settings.

Regards
Dieter (alias Fernando)

Ok it was some issue with identical disks not compatible. I got another seagate disk(same model) and it worked. Now only one issue remains. I am on GPT partition, how do i create logical partitions under RAID 1. I installed windows 10. Thx

The easiest and safest way to create partitions is to use the Disk Management of the OS.

I tried the same thing, but it only creates primary partitions and not logical.