165 is clocked lower than the 3800+ but it more than makes up for it by having double the L2 cache. you can easily (unless you're a screw-up like me) overclock it to past the 3800+, while you can't overclock or do anything ot increase the L2 cache on the 3800. 165 is the better option, and since its socket 939, you can use the same motherboard.