There are more GTX670 and GTX680 firmwares in the thread over at MVKTech (HERE). http://www.mvktech.net/component/option,com_joomlaboard/Itemid,34/func,view/id,63576/catid,10/limit,10/limitstart,0/
Salitus bios'(The creator of the bios and mod) comes in at 1293 stock
All of Tecfreak's bios' come in at 1202 stock boost.(Whom is a helpful fellow on OCN)
Things to do before the flash:
Reset your overclocked settings in all programs you use.
Reinstall NV drivers with clean install(not necessary but some people have had to)
Use this to save your bioshttp://www.mediafire.com/?r95szd1c3dh363r
It is a new version of GPUz that allows so.
you can use this: http://www.mediafire.com/?76z6cfr5d2y7h77
its for the Zotac extreme the install is in Chinese but its in english for the program. It has a built in Flash/Save bios ability and its great.
SAVE YOUR BIOS FIRST! then select flash bios, ok, then select the file from the OP and wait until its done, reboot and your good ! Super simple.
IF for some reason something goes wrong, you can boot off a second gpu(ex iGPU or another dedicated) and reflash the bios you backed up. http://www.youtube.com/feature=player_embedded http://www.youtube.com/feature=player_embedded