I've had a cel566@953 for 6 months now and it's worked great. Core at 1.85, psf-b board. I had to use an asus slocket and that's the only thing I worry about. I don't really trust the temps. The board won't read at all cause there's no sensor to plug in. MB5 picked up on the diodes and the chipsets so I've been using that. Don't laugh but I use a laser temp gauge at work and I brought it home and used it on the chip. It did agree with MB5 so I guess I'm okay. Idle..30c, load..36c. 2 case fans and generic hsf. Anyway, it works.
Don't get greedy like Duckman did, when he fried his Celly][ with 2.1v
I don't know if P3's are more robust, but I've been aircooling my coppermine at 2v for quite some time now, only damage so far has been three blown caps on my BE6-][ (haven't fixed it yet, switched over to the BF6). DO NOT UNDERESTIMATE THE IMPORTANCE OF EVEN A SLIGHT BREEZE ACROSS THE ENTIRE MOTHERBOARD (I did).