How to update Bios in HP Compaq DX6120 MT?

OK well ya have to go to the manufacturers web site here http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=12454&prodSeriesId=402168&prodNameId=402170&swEnvOID=1093&swLang=13&mode=2&taskId=135&swItem=PSG_I22640-107317
Download to say your desktop etc, You then must make a Bootable Floppy disk, with the BIOS file on it. Then using the BIOS manager you run it, you are asked for BIOS name, after which, the software will write the BIOS file to the chip, when it is finished reboot and all should be good. There is more info at that web site too.

Wsam wants more answers to this question
go to Hp.com
tricky URL no?
its there get it from there
and do not get the wrong one or guess, or you brick the PC.
ok>?
best is leave bios alone until you learn why to update and how to do so and not brick a PC.
millions have. and now sad, let your TECH do it , if at all.
ok?
Most PC there are 4 ways to burn BIOS FIRMWARE.
Windows way and bricks it.
DOS way safe as moms arms.
Linux hot boot demo way , safe.
and the Ez burn BIOS update (or like dells, F12 update BIOS)
if you go to any OEM web site, HP.com is yours.
the pages on BIOS tells you which of the 4 ways are supported.
on this old COMPAQ, less ways are supported.
there are over 10 versions of 6100 there, uses you full service tag data to find the correct MATCH or you will be sorry, OK?
last up date 2008, 11 years ago.
this links shows you it is there, but you need to find the exact match. learn that 1 PC may have 20 motherboards, for 1 model, the sub model number on the tag (you failed to stated) shows that. (I do know my BIOS !)

https://support.hp.com/us-en/drivers/selfservice/hp-compaq-dx6120-microtower-pc/456580/model/456581

Hp 6100 mt FI ero probalem