clock speed isnt everything. just like the northwood and prescott cores. the northwood is a bit faster clock to clock speed. also, the xp barton 2500+ is at 1.85ghz and the athlon 64 2800+ is at 1.8ghz. which one's faster? the athlon 64 is far faster and here's why:
it's because amd's cpu architecture composes of a series of short pipelines whereas intel's composes of a series of long pipelines. if you know physics, you will understand this muuch better. because of the shorter pipelines, amd only needs so much frequency (clock speed) to transfer data packets from one end of the pipe to the other. as for the P4, it requires a much larger frequency to send the data from one end of the pipe to the other to match speed with amd's cpu. as a rule of physics, the farther the distance, the farther the frequency is. it goes vice versa also. this also means that amd requires "less numbers" to match the performance of the comparative intel (like cache, clockspeed, etc). the way hyperthreading works is that it fills up the long piplelines of intel's cpu's with data (in the empty spots), so that in the end, the cpu can process one thing and another thing at the same time. this is why multi-tasking is better then amd, but is no where close to the performance of another cpu. as for amd, the reason why they are faster is because of hypertransport and the integrated memory controller. technically, the athlon 64's dont have a front side bus. i guess it's just called hypertransport bus now, but in hypertransport, the system transmit data from the cpu to the memory at 800mhz one way and 800mhz the other way. that is why the hypertransport is 1600mhz. soon, amd will have a hypertransport of 2000. because of the hypertransport and the intengrated memory controller, data transfer rates are increased and memory performance is increased. because of the integrated memory controller, dual channel memory doesnt help much since the memory controller simulates nearly the same performance of dual channel. all in all, because of amd's shorter pipelines, data transfer rates between one end to the other are increased and benefits in gaming (which is very system intensive and requires fast data transfer rates), and the intel "was" better at encoding because of the longer pipelines. with amd's socket 939, amd and intel perform about the same in encoding/decoding (even though anandtech states taht amd surpasses intel on it.). amd and intel's processors compose of tens of different cores, and for amd, the athlon 64's compose of newcastle, clawhammer, and the sledghammer. each have different clock to clock speeds. for example, the clawhammer has 1mb of L2 cache and the newcastle has 512k cache, but it also has 200mhz more then the clawhammer. as for cache for amd, it doesnt matter as much as the P4s (because of the pipelines.)
i just copied and pasted this from one of my posts from this week, so it may explain more then you need to know.