IIRC some P4 boards allowed setting CAS latency to 1... Winbond chips could take it (with some drop in overall overclock), but unsure of others since this was when Samsung TCB3 were pretty popular.

What would be nice is if CAS latencies from 1 to 5 were useable with DDR1 so we could test for an "EB" effect in many different types of chips.