processor speed

[stanzz]

just a simple question. say you have dual core processor, rated at say 2.5Ghz, does this mean your computer actually runs at 5.0Ghz, 2.5 Ghz for each processor? can someone explain?

[FZ1]

No, each core runs at the same 2.5Ghz speed. Multiple cores allow for better multitasking so more work can be done at once which is why it can be faster than a single core for applications that are multi-threaded.

[skier]

multiple cores allow you to do simultaneous work without adversely affecting the speed at which you can do them

say you have a single core CPU, and you have a video game open, the video game will use 100% of your CPU's available power so you can't have another monitor or windows and do other things without one or both slowing down because the CPU can't 'multitask' effectively.

with a dual core or better, you can have a game running and using 100% of one core (only a handful of games are multithreaded currently) which still leaves you with 100% of another core free to web browse or run another game or whatever you want (in task manager, windows gives you a % of total CPU usage, so one core running at 100% would show up as 50% total utilization because the other core is not working, but still included in the total)

[Sttm]

I have been trying to think of a good way of explaining this.

I use a program called Maya, and from to time I have it render out a few hundred image files. A single cpu can only render 1 image file at a time; while a dual core CPU can do 2, or a quad core 4. So even though the quad core, dual core, and single core cpu all operate at the same clock speed of 2.5ghz, the dual core is twice as fast and the quad core 4 times as fast because they can do more renders at the same time. So to match the dual core at 2.5ghz the single core would need to be at 5ghz, and render the images in half the time.

Not every program is able to break down a work load like that and as such the speed difference between the single core, dual core, and quad core shrinks. Some are not written to use multiple cores and see no benefit with just that application; but the number of applications making use of multiple cores has risen rapidly in the past couple years and even games now are really starting to take advantage.

Yet even when an application only makes use of 1 core having multiple cores is still a huge benefit. How often are you running a single program. All the time when I am running Maya I am also running Photoshop, Multiple open windows of Chrome, Windows Media Player, and other applications. So even though many of those applications are not using multiple cores, running them all at the same time does and it does not cause the computer to slow to a crawl and become unresponsive as I remember my old single core system doing.


That was my best shot.

[stanzz]

my dual core uses 2.5 ghz, but i can remember 10 yrs ago when cpu's were running 3-3.5ghz, and mine now only runs at 2.5. that is why i ask.

[Major_A]

I know this doesn't help but a while back there was a rumor that AMD was working on a reverse hyper threading scheme. Meaning you can take multiple cores and "combine them". This was all a rumor and I don't ever see it happening.

As far as pure clock speed, i.e. 2.5GHz now vs 3.5GHz then, it doesn't matter. There are differences in how the cores handle files, new instruction sets, faster interconnect circuitry, and better/deeper caches. The only time you can even compare the clock speed is with two processors with the identical cores, sockets and feature sets.

[skier]

my dual core uses 2.5 ghz, but i can remember 10 yrs ago when cpu's were running 3-3.5ghz, and mine now only runs at 2.5. that is why i ask.

well around 2002 the Pentium4's were up that high of frequencies, but the Pentium4 at 3GHz was still painfully slow because of how it was designed. in modern day the Hard drive is always the bottleneck in a system, but back then the P4 slowed everything down

the Core2 era brought Intel to the top of the performance game. (an AMD single core at 1.5GHz could beat a 3GHz Pentium4 all day long due to its more efficient design) with Core2 you could do a LOT more at lower actual frequencies because applications that once used 100% of the Pentium4 now only used a fraction of that

frequencies may have gotten lower at stock over time, but performance is significantly higher, at much lower temperatures as well