Concerning nForce 2 the subject is difficult to explain.
Biology modding does not do usual necessarily a sense. 
In normal nForce2 BIOS versions everything might be freely eligible for election
what needs Overclocker and a missing option VDD cannot be conjured so mostly
also here.
For waht a custom moddet Bios ? 
Who wants overclock a FSB 266 or 333 processor can profit from to a custom BIOS.
Proved, but often states not necessarily, a mainbaord one FSB 266 or 333 CPU as
such recognizes, bolts from a certain FSB by itself.
Theory or really ?
For really speaks the optimized BIOS version by mainbord supplier DFI and with it
theoverclocking of FSB 266 or 333 processors promotes.
One Speaks from an optimized Bios FSB 200 register.
Fact the DFI nForce2 is as a FSB overclocking King stand there.
With a conventional BIOS DFI a FSB of 270 possible and lightly is about that point
no rarity.
Concret a "optimized BIOS FSB 200 register" to juggle the maimboard, it would
have to do here with 400 FSB processor, no matter which on CPU is on it.
Real tests, what brings this, are not known to me. As a positive example one
can name only DFI.
DFI as a model taken, have copied some BIOS Modder the components from the
DFI Bios in existing Abit or EPoX Bios versions and implemented there.
Known BIOS Modder in the direction is, e.g., Merlin or TicTac.
Also here the same FSB let itself observe phenomenon.
With mod. of an Abit nForce2 BIOS, also reached a FSB from over 270 and an
EPoX 8RDA+ also. Fortuities ?
Also a reason for a custom biology can be it to want to overclock the memory
higher about his normal clock.
In all normal BIOS versions stands the RAM Latency command rate on 1T.
It is not visible really. This Bios option is hidden.
Into the visible Bios menu does not let itself integrate you.
Command rate 1T lies in the complicated appearing HEX Codes of a Bios.
Fact is, memory reaches higher clocks FSB if he on command rate 2T runs.
However, it loses so also to performance because with it a time value is
set upwards.
A partly useful rule is which are necessary 20 to 25 MHz RAM FSB clock more
around, to have the same performance like under command rate 1T to pursue.
If one reaches of hight memory clock a command rate 2T could be have a
better performance than 1T.
Custom Bios versions in the RAM command advises 2 is activated, there are.
Respect to the indication " CPL off ". CPL off is command rate 2 T.
Such a Bios can do sense if I want with the FSB higher, but the memory will not
support an such high clock.
Who wants to wants to find out more about modded Bios, please view in forums.
Put there if necessary questions.
Links for this subject:
Merlin Bios Project
Overview about current Bios projects of Merlin. [Language engl.and polish]
Custom Bios EPoX downloads: 
EPoX 8RDA3+ Optimized RomShip FSB200 Register, BPL 3.19
(CPL/command rate 1T on) by Merlin [Download] Non Pro Version
EPox 8RDA/+ optimized RomShip FSB200 Register (CPL off/command Rate 2T)
by Merlin [Download]
EPox 8RDAi optimized RomShip FSB200 Register (CPL off/command Rate 2T)
by Merlin [Download] Non Pro Version
