Both run at 2.6. I heard this description from someone on this forum.
Imagine if you have 500 boxes that you need to move from one warehouse to another. Each truck can carry 50 boxes at a time. A dual core is like having 2 trucks.
The only problem is that most software right now does not utilize both cores at once. It still helps though because the software that you are running can fully utilize one core while all other applications take advantage of the second core and you don't even notice that you are encoding a movie or something similar.
They both run at the advertised speed (I wondered this myself and confirmed it with diagnostic software after getting my new Dual Core system).
And while previous posters are correct in writing that no individual piece of software currently takes advantage of both cores (if you're running more than one program each can use a core without interfering with performance on the other, but if you're only running one program then it can only utilize one of the cores and the other either does low-grade background application work or sits idle), new video games (and I imagine other software) are being developed using multi-thread programming. This means that the program can be divided into multiple "threads" of computable data so that one program can be essentially cut in half, processed separately with your two cores (thus being finished in half the time), and reassembled at the other end. When this becomes mainstream, a Dual Core computer will move at half the speed of single core even with only one program running.
Bottom line: if you're buying a new processor or computer at this time, you would be a fool not to go multi-core. I notice a significant improvement in load time, speed and overall performance having switched to a Dual Core CPU with the same rated speed as my old single core. Before my system would hang up and be very temperamental when Microsoft Update was scanning it. Now I can run MS Update simulatenously with one or two other applications installing and surf the web with no slow-down
PS: Multi-core processors are also reported to have lower power consumption than their single core counterparts. Go figure.
The 2.6 is just the average. One might be running at 1.4 and the other might be at 4.2. 2.6 is the eaverage. Either way it is much better then a p4, it is basically a pentium 5. Also, the chip is unlocked so that you can overclock, where the p4 was a fixed chip so no-overclocking.
BoomBatz, while we appreciate you trying to help, it is obvious that you have absolutely zero knowledge about dual cores.
As many previous posters have said, each core will run at the advertised speed.
Also, the multiplier locks in place in the P4 family carry over to the PD. There are no multiplier-unlocked PDs that I am aware of (though possibly the PD EE may have been).
There are no enhancements to the PD series over the P4 (other than a process shrink if looking from the early P4s to the PD 900 series), so the P4 to P5 comparison definitely falls flat. The PD is just 2 P4s in a single package, nothing more.
In short, if you don't understand the topic, don't post.