Your ram normally runs at system bus speed, which means that if you have, say, a PIII 866 (133MHz FSB) and you overclock it to, say, 975 (150MHz FSB) your ram will also be overclocked from 133 to 150. Some ram cannot take the abuse, so people have capitalized on selling ram that is garrunteed to work.
The reason I said "normally" is that some motherboards support seperate system bus to ram timing (100/133, 133/100, and 66/100). The ram speed is still increase in proportion to the system bus, the base speed is the only difference.
Suicide is painless...........