Please check your existing bios version first. Boot up with your on-board graphics and on the boot screen, hit the pause button and you will see the Award Bios details on top of the screen with the version mentioned. Alternatively, boot into Windows and use CPU-Z to check your Bios version under the Mainboard tab.
There is a version F6 and version F7 bios available for version 1.5 of the motherboard - GIGABYTE - Motherboard - Socket 775 - GA-G41MT-S2 (rev. 1.5)
There is a version F6 and version F7 bios available for version 1.5 of the motherboard - GIGABYTE - Motherboard - Socket 775 - GA-G41MT-S2 (rev. 1.5)