judging by your clocks i guess you have the gigabyte 460 OC version?
i do too, unfortunately i dont have 3d mark vantage but i can confirm renz's statement.
the 460 can have a clock speed of 850 and up to 920 if you over volt it (which means increase the number of volts the graphics card uses)
make sure you keep an eye on your temps and dont oc your card too much or you might break it (rarely)
I am fine overclocking the core and memory clock, but am hesitant about overvolting, just because I don't know how much I should increase that by. Is there a guide or standard to how much you would increase the volts by anywhere? Thanks.