Dell optiplex 990 MT HDD not showing in Win10

If the drive is new, it needs to be partitioned and formatted before Windows will see it.

support.microsoft.com/.../windows-7-create-format-hard-disk-partition

The 990 is not UEFI bios and the Chipset in the unit is TOO OLD to be supported by the most recent INTEL RST AHCI driver.  This means F6 mass storage Drivers are Required to "SEE" the advanced format drive.(Any drive after 2011 and over 120 Gigs)

The product name was changed from Intel Matrix Storage Manager to Intel RST
v5.5.0    2006    Last version to support ICH5
v6.0.0    2006    Included on P965 chipsets with ICH8R southbridge
v8.0.0    2008    Standard on Intel X58-based motherboards.
v9.6.0  2010    Required for Advanced Format Drives
v10.1.0    2011    Last version to support ICH8  Required for Drives larger than 2TB
v11.7.0 2012     Last version to support ICH7R and ICH7M, ICH9M, ICH10R and ICH10D

This manifests in multiple ways.

Fairly sure that version 15 RST is Too new.

https://downloadcenter.intel.com/download/26865/

 

They drop more and more chipset support with each version.

They dropped ICH7 in version 11.3

 

OptiPlex 990 Technical Specifications

Intel ® 2nd Generation Core™ i7, i5, i3 Processors. Intel vPro™ Technology available on select processors

Chipset

Intel ® Q67 Express Chipset

Operating System Options

Microsoft ®   Windows 7

Windows Vista

Ubuntu ® Linux ; FreeDOS for N-series

Video

Integrated Intel ® HD Graphics 2000 [with iCore Dual/Quad core class CPU-GPU combo];

optional 1GB AMD RADEON HD 6670 (MT only);

optional 1GB AMD RADEON HD 6450;

optional 512MB AMD RADEON HD 6350

There are of course many other versions.

• 15.5.0.1051
• 15.2.0.1020
• 15.2.16.1060
• 14.8.0.1042
• 14.0.0.1143
• 13.6.0.1002
• 13.2.4.1000
• 13.1.0.1058
• 12.9.0.1001
• 12.8.0.1016
• 12.5.0.1066
• 12.0.0.1083
• 11.7.0.1013

 

9.6.0.1014 to 10.1.0.1008 may be the only version that works.

https://downloadcenter.intel.com/download/15251/

 

https://downloadcenter.intel.com/download/20104/

 

 

Download the driver STOR_allOS_10.1.0.1008_PV.exe and one of the following F6 driver diskettes, depending on your operating system:

• STOR_F6_32_10.1.0.1008_PV.exe - for 32-bit versions of Windows 7*, Windows Vista* or Windows XP*
• STOR_F6_64_10.1.0.1008_PV.exe - for 64-bit versions of Windows 7, Windows Vista or Windows XP
  

 You cannot POINT to the EXE you have to extract it to a floppy OR USB FLASH DRIVE.