hmmmm
Interesting that both OCZ and Kingmax score exactly the same for you... Try pulling all your pci cards out and see if you can overclock it higher. If you can get higher, test each card one at a time and see what's holding you back. Might be voltage to either ram or cpu that you need. My 1600+ needs 1.9+ volts to go above 1.6Ghz.
Another option to try to get it higher besides a volt mod, is to run lower fsb with an 10.5x or 11x multiplyer (what I'm doing).
As for not getting as high on the mem bandwidth score as some other ppl... might just be differences in motherboards. I get about the same mem score as you(maybe a bit higher), but at 148 FSB, on my OCZ PC2700.