Yes, totally sure. It's also 501/1500 when playing a flash video.
My clocks and voltages:
#0 Core Clock: 975, Memory Clock: 1500, VDDC: 1256
#4 Core Clock: 300, Memory Clock: 150, VDDC: 950
#5 Core Clock: 501, Memory Clock: 1500, VDDC: 950
#6 Core Clock: 925, Memory Clock: 1500, VDDC: 1188
#7...