I have 2 cC0 celeron 600s. So far, one is still sealed, one is on a CUSL2 at 900mhz running fine so far, 1.7v (default), with options to go up to 2.0v on the CUSL2 (allows .3v above default). I will run stress tests and see how well they oc, but so far, 900 out of the box, 1.7v seems very stable. Althou they didnt work on my BM6, which could mean new mobo for some owners ( >.< ).