First off, the mem always posts as half its rated speed. DDR (Double Data Rate) take your 400 and double it = 800mhz.
As for 8pipelines.....you sure you didnt buy a 6600GT?
Because if your cards are 8 pipe parts, then you need to get your $$ back.
Sometimes benchmark utilities can be a little screwy, so it doesnt mean your card is missing components...anywho;
Want to overclock? Rivatuner, coolbits or ATI tool basically.