How do I set Optiplex 780 bios A09 to LBA mode?

Spinrite is 20 year old MSDOS software. It is not supported here.

https://www.grc.com/sr/kb/sata.htm

Many Dell bios have had 48 bit LBA mode since 2004 and ALL after 2005.

There is no BIOS setting for LBA.

There are sometimes SATA operation modes for ATA instead of AHCI.

Msdos FAT does not support native AHCI nor does it support drives larger than 8 gigs.

The BIOS of most SATA motherboards contains SATA configuration options that can be used to cause the hardware registers of new SATA drives to "appear" in the locations occupied by traditional parallel IDE/ATA (PATA) drives. These options are typically called "Legacy" or "Compatibility" mode. These options have been created to support older operating systems, such as Microsoft Windows 9x family, which are incompatible with SATA drives unless they are "mapped" into the traditional IDE hardware locations.

Although this is the first thing we will be fixing with the v6.1 release of SpinRite, the first v6.0 release of SpinRite has the same limitation as earlier versions of Windows and other operating systems.

Note that while your motherboard is configured in "Legacy" or "Compatibility" mode one or more of your SATA drives will replace any IDE/ATA drives that have been "mapped over" for the sake of compatibility. Your motherboard's mode will determine which drives are visible to SpinRite.

If SpinRite is not showing SMART data for your SATA drive(s) and your motherboard's BIOS does not offer any SATA compatibility options, or if you're using an add-on SATA controller which is not showing SMART data, there is not currently any way to force SpinRite to access SMART data of drives at non-standard hardware locations. As mentioned above, all of SpinRite's maintenance and data recovery operations will work even so, but SpinRite's continuous on-the-fly SMART polling will not be available for those drives.

Since this is a rapidly growing problem for SpinRite, due to the market's rapid success and uptake of of SATA drives, we are considering the development and release of v6.1, which will cure this problem, sooner rather than later. The upgrade to v6.1 (and any other "dot releases") of SpinRite will be no-charge and all registered owners of SpinRite will be informed as soon as v6.1 is available. This is not something we have started work on, but it has a high and growing priority.