That's right, Shag. The memory clock equals 2000 when you set it at 1000 in your settings. Please don't ever try to run ANY card at a 1500 Mem clock. I'm green myself, but I'm pretty sure you'd ruin your card doing so. That would be a 3000 setting (1500x2). The core clock and shader clock numbers are not doubled tho'. My EVGA version of your card is running at 651(core)1000(x2=2000 mem)and 1525(shader) with no voltage boost. I hope you can get more out of it, but what I've read in here is to bump your clocks slowly (core +3 at a time and mem +5 at a time) then use a benchmark program (I use 3DMark06). If it runs without relics (jjagged lines or blocks of color that don't belong) bump again and test again. When relics appear down clock to a stable setting and that is your max speed. Don't run it with relics long (Escape button will abort 3DMark!) or you may do damage to your card.
Good luck and play safe