(Forward from: http://vip.asus.com/forum/view.aspx?id=20070215223109668&board_id=1&model=P5B+Deluxe%2FWiFi-AP&SLanguage=en-us&page=1)
Updating BIOS is serious business!
Every precaution should therefore be taken to prevent that anything goes wrong. Above all: DO NOT USE ASUS UPDATE!!! AFUDOS is the only good alternative to EZ Flash 2.
EZ Flash 2 is a built-in function of BIOS. It is the safest way to update BIOS, because one is not dependent on the operating system, any application, internet connection, firewall settings, antivirus or anything else that can put the vital BIOS update at risk.
On a new build, BIOS can be updated to the latest version before installation of the OS, which may possibly make the installation go smoother and safer.
Note: All what’s said below about loading BIOS defaults also applies to the other BIOS update methods (ASUS Update and AFUDOS)!
The PC must never be overclocked during the BIOS update! Always load and save BIOS defaults before and after a BIOS update (press F5). By loading and saving BIOS defaults before the update, CPU frequency, memory frequency and voltages are set to default (Auto).
Memory timings are set to SPD values which ensure that a PC with high performance memory that need a higher voltage than 1.8V for DDR2 or 1.5V for DDR3 is able to boot on the standard Memory Voltage. Save the default settings (press F10) before starting the update.
When these instructions are carefully followed, there will be no need for a CLRTC.
Document all your preferred BIOS settings (i.e. the settings you have changed from the default setting).
Download the BIOS file, which normally is compressed (zipped).
Unzip the BIOS file to a FAT/FAT32 formatted USB Flash Disk with only one partition
(or to a Floppy Disk or a CD-ROM).
If the unzipped BIOS file is named like e.g. ‘P5B-ASUS-Deluxe-1101.ROM’,
you can rename it to ‘P5BD1101.ROM’. Otherwise a truncated name will appear as ‘P5B-AS~1.ROM’ due to a limitation to max 8 characters in the filename (8.3).
Press (tap) DEL during POST (Power-On Self Test) to enter BIOS Setup.
Load BIOS Defaults (press F5).
Insert the USB Flash Disk containing the BIOS file P5BDxxxx.ROM. (Note that the USB Flash Disk has to be inserted before boot to enter BIOS, otherwise it won’t be detected).
Save and Exit F10. (BIOS will now restart).
During BIOS restart, press DEL to enter BIOS Setup again.
Under Tools menu, select ASUS EZ Flash 2.
It may take 20 seconds for the drives to show up.
Select a drive in the left pane
Select the BIOS file (e.g. P5BD1101.ROM) and press
Supervise the update, which includes the following stages: Erasing – Flashing (writing) – Verification.
BIOS will automatically restart when the update is ready.
Disconnect the USB Flash Disk before/during the restart.
Perform a C.P.R. (CPU Parameter Recall) which resets the chipset.
Power down, remove power cord from the PSU for 2 minutes and then power up.
Enter BIOS and load BIOS Defaults
Reenter your preferred BIOS settings – if you are using AHCI or RAID mode, don’t forget to set ‘Configure SATA as’ to [AHCI / RAID]. Also remember the settings for the JMicron Controller, Audio and Memory Voltage. Check also that the Boot Device Priority is ok.
Save and Exit
Press DEL to enter BIOS Setup and make a final check that all BIOS settings are ok. Save any changes.
In case of a new build:
When BIOS is updated to the latest version, and prior to the installation of the operating system, run Memtest86+ (v2.11 or later) for a few hours to check that the memory test doesn’t report any errors.
There are precompiled bootable downloads for Floppy Disk and CD-ROM (ISO).
Memtest86+ v2.11 released December 23, 2008
http://www.memtest.org/download/2.11/memtest86+-2.11.floppy.zip (Bootable Floppy)
http://www.memtest.org/download/2.11/memtest86+-2.11.iso.zip (Bootable CD)
(The unzipped ISO file is burnt as “image” on a CD)