Just got one too at 700/1100 default core/mem clock settings. I'm using 3Dmark06 and rivatuner to stress the card for O/Cing runs. At the card's default clock and fan setting, it runs up to 90C, with with SM2/3 scores of 5050/5000. No problems. Sounds a bit warm, but that's not my call. This is all Nvidia 'plug 'n run' in a 70F ambient room . . . and it runs fine.
To control temps during initial O/C runs, I set the fan to 100% with riva. Gcore temp stayed at 70C, but the card would not complete a 3Dmark run at 825/1100 (core/memory). It will not run at 825, temp was not factor here. That's my chip's top stop.
At 800/1200, it ran fine and completed all 3Dmark runs with SM2/3 scores of 5490/5240. Temp remained at 70C.
That fan is really noisy at 100%, so I started to slow it down. I found at Any core temp above 70C (@ 800/1100), 3Dmark would artifact/freeze. I experimented and found that a fan speed of ~ 75% finally tamed the temp down to 70C and allowed 3Dmark to complete.
The SM2/3 scores were about liner with the O/C. ~ 5%. It needs the fan at 75% to maintain a stable O/C, but is right on the edge. Anything > 70C starts to artifact. So
1) That required increase in fan noise,
2) plus no temp headroom for increased summertime ambient temps,
3) plus a virtually undetectable 5% performance boost,
4) plus "balancing" down to a more sustainable O/C renders any performance increase even more undetectable =
O/Cing this card is primarily for the fun-factor, but (pragmatically) is really not worth the trouble.