Depends on the silicon lottery but I've undervolted mine by 15mv and I've also overclocked it to 1025/1550 so could probably undervolt it a bit more at stock.
The overclocking is pretty pointless, only a slight gain in benchmarks and nothing noticable in games but it just doesn't seem right to have a card running at stock when I know it could be overclocked
Mine happily worked in Crysis 3 at -30mV on 1440p Very High for a good session, so it's worth a try. It made about 1 degree of difference to temps I think, but I wasn't exactly measuring in a controlled environment.
On the subject of throttling, I found that even exhausting through mesh on my case reduced airflow enough to throttle my card. I removed the mesh and it has never throttled since. Check there is an absolute minimum of obstruction to the rad as it exhausts the hot air.
