BIOS does not recognize 2 of 3 HDDs

[atokuno]

I have built a PC with the following components:
CPU: Intel I7-6700
SDRAM: G.Skill TridentZ series DDR4 16 GB SDRAM, PC4-27200
SSD: Samsung 512 gB VNAND 950 Pro M.2 NVM Express
Motherboard: Gigabyte LGA1151 GA-Z170X-UD5 with
Intel 100 Series/C230 Chipset SATA AHCI Controller for ports 0-5
Asmedia ASM1061 SATA Controller for ports 6-7
CD/DVDW-ROM: TSST TS-H653L
OS: Windows 10 64-bit Home Edition, ver 1803 OS Build 17134.407
BIOS: Gigabyte UEFI DualBIOS ver F5
HDDs:
1 TB Western Digital Caviar Model WD1001 FALS 00Y6A0
2 TB Seagate Barracuda Model ST2000 DM006 new
250MB Western Digital Caviar Model WD2500JS 60NCB1 from an HP1640

System boots up fine but BIOS does not recognize the 2 TB Seagate HDD or the 250 MB WD HDD. Both are known working, spin up fine in the system with the data cable removed. In BIOS, the SATA ports for both are enabled. Data cables have been replaced with the known working cables for the CD ROM and the 1 TB HDD. SATA ports have been swapped with the CD ROM and 1 TB HDD. There are no jumper cables on the back of any of the SATA HDDs.

So why don’t these drives show up in the BIOS, Powershell queries or Device Manager?

 

[Dark Lord of Tech]

* Refer to "1-9 Internal Connectors," for the supported configurations with the M.2, SATA Express, and SATA connectors.
When running an M2 a couple of SATA ports will be disabled , check your manual or download the online version to check which ports are disabled.

 

[atokuno]

I also swapped SATA ports. The same drives worked, i.e. 1 TB WD and CD-ROM, and the 2 TB Seagatre and 250 MB WD HDDs still were not recognized by BIOS.