Update:
I contacted Gigabyte support and they kindly sent me a Bios for the GA-X48-DS5 (Bios version x48ds5.8b3), which now shows a 'Security Chip Configuration' option in the BIOS set-up screen.
Unfortunately, when the chip is enabled in the BIOS the system hangs after reboot:
What is frustrating, is that it runs through the normal boot process and then hangs showing a blank (black) screen just before it displays the BIOS boot screen that shows the component IRQ assignment and subsequently the message 'Verifying DMI Pool Data'.
If I remove three of the four 1GB RAM memory modules the BIOS boot process gets stuck showing a different screen i.e. It displays the detected AHCI drives list and brings up the 'AHCI BIOS installed' then simply a flashing cursor under this.
The system can only be retrieved by doing a hard reset, all keyboard inputs are ignored.
I have tried a different GC-TPM chip and get the same result so assume it is not the chip that is faulty.
If I disable the TPM chip in the BIOS the system responds and boots as normal without problems.....
It looks to me with my basic knowledge of BIOS image programing that the memory or IRQ map in the BIOS image given to me by Gigabyte is incorrect somewhere and causing a conflict with another motherboard device. I have come to this conclusion because of the difference in hanging boot behaviour when RAM modules are removed or installed.
So this looks as if I am at the mercy of the Gigabyte techs to correct the problem in the BIOS image they sent me.
Will keep this post updated. This info may come in useful to someone else one day!?