My god I cannot believe the bad advice here.
You don't have to update your BIOS to add memory, as everyone has said, but....
unless you are having a specific problem, and a new BIOS update has been written to specifically fix the problem you are having....LEAVE YOUR BIOS ALONE.
"If it ain't broke, don't fix it" is the golden rule of BIOS updating.
I don't know over the years how many threads have been posted where people have killed their motherboards trying to update their BIOS. Many, many, many of them. And no telling how many people otherwise have done it as well. It is probably one of the biggest single causes of motherboards being returned as dead.
Thats right, if you don't do it correctly, you will have a dead motherboard. Period.
The only way to fix it is a new motherboard, or have the motherboard manufacturer send you a new BIOS chip, if your old chip is removable.
Your BIOS does not contain any programs, drivers, or anything else that affects your systems performance. Your BIOS simply configures, or allows you to configure, everything that you have. A BIOS update is usually to allow for some hardware configuration that was released after your board was made, like a new type or family of processor that fit's on your board.
Memory is not one of the things that normally require BIOS updating.