LN2 is defintely cheaper, yoiu ust tend to kill things when you use it....
Most of the top guys at 3dmark 2003/2001 kill there graphics cards after a few runs with big memory overclocks.
This
CPU should run a high clock or a long time, ATM im running 2.8gig at 1.925v stable, shame this rev 2 8rda wont ive me any more