Hi,
since bios version is "F5".. so what does that mean.... ?
Basically when a motherboard is released it comes with a version of BIOS that handles the majority of CPU's available at the time of its release. As CPU manufacturers, both Intel and AMD, release new CPU's the BIOS needs to be changed so that the motherboard can handle the new processors. In the CPU compatibility charts on Gigabyte's Website they use the term "Since BIOS" to show which version of BIOS you need to run a certain CPU. You have stated that for your chosen CPU you need the motherboard to have BIOS F5, so you have to have at least that version or a later one (F6, F7 etc.,) to enable you to use the CPU, anything before F5 (F4, F3 etc.,) will not support it.
If you do buy this board you will need to make sure that it will handle the CPU that you are buying or, as you have said, you will need a CPU that is supported by an earlier version of BIOS so that it can be updated. The best thing to do is check with your supplier and ask them to make sure that the BIOS on the motherboard is version F5 or later. If they are supplying both the Board and the CPU, if there is a problem when you come to install it at least, by having asked the question, you will have some recourse if it doesn't work. Why spend money on another CPU if you don't really need to.
Hope this helps.
ATB