I believe it to be different for each PC depending on the CC company and the nature of the PC. From what I've read, it depends on whether the network changes (i.e. VISA to MC), and whether or not they have to change the acct number (like from regular MC to World MC).
AMEX Blue Cash - $15k, Lowes/GECRB - $10K, PNC - $10K, CIti Diamond Preferred - $10K, Home Depot/Citi - $7590, Best Buy Store/HSBC - $7400, Citi Platinum Select - $7150, Best Buy RZMC/HSBC - $5750, Dillards/GECRB - $4350, Discover More - $3600, Cap 1 Cash Rewards - $3000, Amex HHonors - $2000, State Farm - $2000, Cap 1 MTV - $1500