To flash the latest BIOS:
I must point out here, that there is inherent risk in this. If, say, the power goes out during the process, or your CPU isn't supported properly by the existing BIOS, there's always the possibility that you could 'brick' the board, i.e., turn it into something only suitable to prop open a door... However, with proper technique, the odds of success are very high - and, short of having @BIOS 'die' in the middle of a flash, the built-in recovery stuff (dual or quad BIOS, XpressRecovery, etc.) is very good. I have dumped my BIOS twice (due to a corrupted file) and both times my board simply reverted to the 'as shipped' BIOS, and continued to work fine. Processor support isn't a problem here...
That said, you can get the latest BIOS here:
http://www.gigabyte.com.tw/Support/Motherboard/BIOS_DownloadFile.aspx?FileType=BIOS&FileID=14748
and you will wind up downloading a file named "mb_bios_ga-m52l-s3p_f2d.exe"; easiest way to do it is to create a folder on your desktop, named, say "NewBIOS", and put the .exe into it. Then, open it, and run the .exe; it will extract to three files: "M52LS3P.F2d" (the actual BIOS binary), "FLASHSPI.EXE" (the BIOS 'flasher' executable), and "autoexec.bat", which can be used to make a bootable, self-loading BIOS flasher disk.
There are a few variations of three basic methods to flash the BIOS. One is the included, windows/inet based utility "@BIOS"; NEVER use this! BIOS flashing has its own risks built-in; you really don't want the possibility of a windoze crash added to them. Every time I post this, someone, without fail, will pop up and say "I use it all the time" (which usually amounts to, maybe, twice), or "I've never had a problem" (once); my response is that you can play Russian Roulette, too, and live to tell about it; you can pull the trigger once, and just get a 'click'; maybe the second time, also - but by the third pull, the odds are stacking up against you, and if you keep pulling that trigger, you will blow your brains out!
The easiest WAY: "<F8> Access the Q-Flash utility" from the main BIOS page, and avoids having to rely on a loaded OS to work correctly to do the flash. If you have a floppy drive, copy the "M52LS3P.F2d" file to an empty floppy, reboot, hit <DEL> to enter the BIOS, hit <F8> to enter the flasher, the first place it will look for the new BIOS is, I believe, the floppy - select the file - it will verify the file, flash, verify the flash, and offer you a keystroke to exit the utility and reboot... If you don't have a floppy, put the file on a USB keydrive, enter the flash utility, and navigate to it; if it doesn't seem 'reachable', you may have to reboot, enter the BIOS, and go to the "Integrated Peripherals" page to enable "Legacy USB storage detect" - remember to disable this after the flash, as it is known to cause wierd problems, including the dreaded "reboot loop"...
Last, but not least, a 'bootable' flasher; if you have a floppy, this is only a little more complicated (but I don't see a real need for it - the BIOS' built-in facility is more reliable, easier, and, if your system is so cooked that it won't enter the BIOS, it's damned unlikely to boot anything)... You need to start out in widows, and format a floppy, checking the "create an MS-DOS startup disk" box; then, open the disk, and erase everything but command.com and msdos.sys to make room for the BIOS goodies; copy the three files your BIOS expanded to, to the disk. Next, a reboot, and a <DEL> to enter the BIOS - go to the "Advanced BIOS Features" page, and set "First Boot Device" to "Floppy", put the floppy we created into the drive, save and exit - on the reboot, the flasher should autoload and 'do' the BIOS; be sure to give it enough time to finish - rebooting during the process (and for some versions of the utility, it doeasn't give you a lot of feedback!) puts your MOBO 'at risk'... If you don't have a floppy, and want to create a bootable USB 'flasher', post back - that gets a little more complex, and I'd like to limit the 'scope' here.
No matter how you've done it, the very first thing to do, after booting to your brand-spanking-new BIOS is to do an "<F7> Load the Optimized BIOS default settings", or simply cursor to it and select it, and then re-boot again; if you still have troubles, try the "<F6> Load the Fail-Safe BIOS default settings" likewise...