Let me repost this for clarification
Maybe Michaelrw can add this to OP as well..
I think this is correct...
LN2 BIOS is around 50mV higher than the standard BIOS.....
Standard BIOS = defaults to 1175mV with no overvoltage
LN2 BIOS = defaults to 1.21V with no overvoltage
Standard BIOS = 133% power
LN2 BIOS = up to 300% power
Standard BIOS = boost depends on your chip
LN2 BIOS = boost is always 1202
Standard BIOS = obeys driver voltages, goes up to around 1.325V with 2.2.3
LN2 BIOS = goes a bit higher, goes up to around 1.35 or 1.37V with 2.2.3Standard BIOS= has kepler throttle and overcurrent throttle!
LN2 BIOS= has *disabled* all throttle mechanisms and is ultimately more stable with maximum overclocks
Kepler throttle is a mechanism on all 680s which lowers clockspeeds in 1 bin increments when you hit 70C ! This can lower the effectiveness of your overclock, although hitting 70c is NOT LIKELY with TF4 (with a good fan profile) it is possible. Thus LN2 prevents this. Increasing voltage always gives a noticeable increase in temperatures but its never bad with a single card. With SLI you'll become more temperature limited , depending on how close your motherboard requires the cards to be to each other...if you can place the cards far apart it may be a non issue.
Temps only differ between normal bios vs LN2 because LN2 always has like 50mV higher voltage, all other things equal (I think,...have to double check)There is also no difference between 3a BIOS and original BIOS for overclocking, despite the initial belief. 3a has a less aggressive fan profile at startup.
AS always,1)-overclocks depend on luck partially
2)-You should always use manual fan 70% or higher for maximum overclocks especially with voltage
3)-SLI will cause more temperature limitations (not an issue for single card)
4)-If using SLI create maximum distance between cards and improve case airflow
5)-Do not use auto fan for heavy OCs! ANYTHING 1350 or higher should be at least 70% manual fan
6)-SLI overclocks will NOT be as good as single card overclocks
7)- As always, voltage adds higher temps - for 24/7 find an overclock that uses the least overvoltage possible is the best bet IMHO
Happy overclocking Edited by xoleras - 7/28/12 at 2:57pm