stock cooling is good, but prolonged life might dwindle... I wouldn't run intensley like that for one reason:
1) Todays games don't need that much oomph from these cards. Stock speed is fine.
When the more complex games come out here soon, we will need the OC'ing and if we OC now, we won't have these cards. Remember, you did drop a bit of cash into these cards, don't light the fireworks until the 4th...? I mean don't ruin the cards before the real games hit the shelves.
my $.02
steveD