the highest so far i think is morphling's overclock of the JIUHB 0251 at 2.8ghz

JIUHB 0302s are doing very well ..... got 1 of these a green 1

2.0ghz at 1.65vcore
2.1ghz at 1.7vcore
2.2ghz at 1.825vcore
2.3ghz at 1.9vcore but too hot for my cooling system