Not really sure about these 980 Ti`s..
I`m already running reference 980s at 1574mhz/8ghz in SLI - gives 23500 in Firestrike.
I can easily push one of my cards beyond 1600, but the other card with lower ASIC can`t take it..:(
Not convinced the 980 Tis are worth it unless you can perpetrate some serious cooling. That means at least chilled water cooling with a serious aquarium cooler- at the very least.
With air and ambient water cooling, these cards don`t seem to deliver.
Waiting for pascal seems the better option.
Though to the OP i have to say- messing with the BIOS and finding out what all the sliders mean, maxing your cards OC potential, is SERIOUS FUN! You`ll crash your PC a million times, but it`s great seeing those firestrike results go upwards..:)
Wish you good luck..:)