Overclocking is nice, whats the max the 8800gt can be overclocked to??

Even though the following message looks should have been posted some 4-5 years back, i cant help it . Yesterday only i looked into riva tuner and other overclocking tools and overclocked my Fx 5200 and it was very interesting and happy to c some good results. My card has the factory setting at 250Mhz core clock and memory at 350 and i use to play Ea sports FIFA 2007 @ 1024*768 medium settings and i get 38-42 fps (fraps) and after overclocking it was giving around 41-45 fps and the picture quality was little bit improved. I overclocked it to 280 core and 378 memory and when i gave the max speed in riva tuner the display went off so had to restart the pc...

Reason for this post is that i am getting 8800gt this saturday (pc components r ready, need to get it from the dealer) and want to know whats the maz safe limit the 8800gt can be overclocked such that it doesnt hurt the card and thus the whole machine.. Thanks!!!!!!