Confused with GHz and Processors

Hi everyone...

I could've sworn I read somewhere that a 2.0 GHz Intel Pentium 4 processor is not the same thing as a 2.0 GHz Core Duo. Is this true?

I thought that GHz was a set speed, kind of like "a ton of cotton weighs the same as a ton of steel".

So is my dual processor 3.0 GHz Pentium 4 slower than a dual-core 2.16 GHz Core 2 Duo?

 

Your dual CPU p4 at 3ghz is slower than the slowest 1.66ghz Core 2 Duo. Its just a matter of better design, newer technology, and witchcraft when it comes to processor designs.

 

GHz is a set speed in a way. But it's in no way a set level of performance.
By that I mean that the clock speed (in GHz) determines how fast the CPU "ticks", but it says nothing about how much work the CPU can do per tick.

The clock speed doesn't mean anything to the user (there's no inherent advantage to having a CPU with a faster clock speed. All that matters is how much work it can get done)
That's the factor that's been improved the most in the last couple of years, to the extent that yes, a 1.6GHz Core Duo can easily beat a 3GHz Pentium 4.

Someone here compared it to trucks vs cars. A car might be faster, but if you need to carry a lot of stuff from point A to B, a truck is still much more efficient

 

The way I describe it, and it's not totally accurate and it does not take everything into account, but the Pentium 4 was a marketing sham and a not that good CPU. Look, our chip goes to 4GHz! It must be the fastest!

The Pentium 4 is from the era when Intel lost its way. To win the marketing wars, the Pentium 4s achieve high clock speeds but the way it did it pretty inefficiently.

Think of a highway (for program code to travel on) with nice long straightways so you can travel at high speed but there's not a lot of exits on the freeway. When you pass an exit, the next exit is pretty far away, so you are traveling fast, but you have to drive a long way to exit. The traffic kind of sucks, so, sometimes you miss an exit since you can't get to the exit lane. Heat makes your car slow down, and sometimes the road is not a long straightaway and you have to drive over a mountain range. So even though you can go a 3GHz, you kinda gotta slow down a little to the get around curves and mountains.

New new CPUs run a little slower, but the highway has plenty of exits, you're in smaller more lightweight sports car and dart in and out of traffic, and you can basically rip stuff up fast and furious style.

So, in a race to the milk store, the slower processor wins since it travels on more efficients freeways, the car is a little more nimble and there are less things getting in your way. The slower CPU gets better gas mileage and makes less heat.

Think turbocharged Turbo Elise vs. Dodge Chrysler Hemi. Hemi has a lot of horsepower, but the Lotus Elite turbo is going to kill it in most road races in the real world, ie, curvy roads with traffic. You'd also rather drive the Lotus Elise since it's more fun. Pentium 4 is all baller, but you gotta cruise real slow and makes lots of exhaust rumble, but you're not all that fast.

 

i think jalf's analogy is more understandable...

and an elise (untill the latest version) were HORRIBLE at handling though they go fast.


i would suggest anyone who'd like a more indepth understanding of how you can't rate a processor by it's clock speed to read this:

http://en.wikipedia.org/wiki/Megahertz_myth

DON"T LET INTEL"S (p4) MARKETING CRAP FOOL YOU!!!

 

Ok look at this example. Given a p4 2ghz and a core duo 2ghz, the simplest way to explain it is core duo has 2 processor making it 2ghz + 2ghz = 4ghz. Although is not exactly correct but at least it explain stuff for ppl who r new to this. But given a 4ghz P4 vs a 1ghz 4 cores, i ll take the 4 cores anyday since it can multitask really well. But if is like a single core app, there s a possibility that the 4gh single will smoke the 4 cores.

 

NOOOOOOOOOOOOOOOOOOOOOOO

lunateck is wayyyyy off

you don't go 2ghz+2ghz to measure the actual performance level of a cpu.

a single core solo would still beat a p4

this is because a core 2 duo is 2ghz x 2, which means there are 2 cores and they BOTH run at 2ghz

a core 2 duo is better not only because it has 2 cores, the architecture is more efficient then p4.

the 2 cores help it multi task better then a single core.

both cores still run at 2ghz thus when you have two threads running that just means each of those threads are run though different processors at 2ghz

the PERFORMANCE of a processor depends on it's IPC and clock speed. very low IPC and a high clock speed = p4 = crap. core 2 duo has more IPC is more power saving and though a lower clock speed then p4 is still pretty high = current best cpu



as i have said Jalf's analogy is pretty good.

let say you want to get 1 ton of stuff from point a to point b.

with a p4, you have a mclauren f1, super fast but not much cargo room and even though you go fast you gotta make a lot of trips (high clock speed low IPC)

with a core 2 duo, you got a truck on steroids + turbine engine + turbo + solid state rocket on the back. while the truck will be slower then the mclaren f1, it can carry the 1 ton of stuff there in 1 trip, resulting in much faster performance of the cpu.

 

That was me And my analogy is:

A processor basically moves data and transforms it. A Pentium 4 is like having lots of little cars running very fast back and forth. A Core or Athlon based processor is more like having fewer big trucks running back and forth. They don't go quite as fast, but they carry a lot more data with them with every trip. So overall, the trucks are more efficient.

 

let me ask you lunateck, does 2 xeon processors on a dual processor motherboard running at 3ghz mean that it's equivalent of a single xeon processor at 6ghz?




let me give you a hint

the first letter of the answer is N and the last letter of the answer is O


good analogy pitabred

 

Well, I understood it fairly well before, but now I understand perfectly thanks to hmmmmm and Pitabred.

 

this is the best description of this concept that i have read yet. It makes sense to me.

 

Ummm.... NO. That's wrong on SO many levels. Can 9 women make a baby in one month?

Dual cores is like two women making two babies. Both will still take 9 months, but you'll have two babies at the end of 9 months, rather than getting 2 babies after 18 months if you only had one woman making babies.

It takes a guy too, but that's not germane to the example

 

How about men cooking dinner instead of women making babies?

Oh wait that's impossible!

GHz is really a way of denoting speed for a particular model of CPU but it has little correlation between different models, there are too many other factors like architecture, cache, cores blah blah blah.

 

No, it's not, I cook dinner at least once a week.

 

Yes. But if you compare a Core Solo to a Core Duo, my comparison is correct. A Pentium 4 just does less work per month, but it's months are shorter

 

I was implying a change of example might be prudent.

 

Stop the P4 bashing!

Northwood was one of the best processors ever.

 

Ermmm... my style of explaining stuff is to noobs... not to experts like you. You know i meet a lot of hardheaded old ppl which insist a P4 with 3ghz runs faster than the core duo 2ghz. It is just simpler to explain this to them. But after i saw some of ur explanation, i think i can explain it even clearer to them. Thanx!

Now let's have a even confusing question. Will a native 4 cores beat a quadcore that intel has now? How do you explain that?

 

I had 3 Northwoods, a 2.2, a 2.8 and a mobile 3.06 and they all performed pretty well. It's true that they ran hotter than the athlons i had (even with an XP-90) but they did feel... reassuringly meaty.

I'd not diss them, they are good cpus!

 

Native 4 cores? What? You mean, 4 processors as compared to a quad-core? They should be very, very similar in performance, if the cores have similar performance characteristics. I have a hard time believing that a 2.2GHz Pentium was good for much of anything but a doorstop. If you had tried an Athlon64 of the same vintage, you'd understand.

I also have a dual-Xeon system (see the sig), and though the chips are fairly fast, they still have nothing on my notebook. The Intel Core and AMD K8 architectures are MUCH faster than any Northwood, as well as better from a design standpoint.

 

I ve tried Intel processor for the most of the time, but i did tried out a Athlon XP, which is really good at overclocking. Now i m still using the Prescott, and it's really a pain in the as*. Anyway, i have my budget, i ve still not own any core duos but i ve played with it already.

Like you said the architecture changes from time to time, they improve thus making some of the old technology like FSB, nearly outdated. I ve read that intel will get rid of the FSB in the near future, as its limit are reached.

 

A "real" quad-core will beat what Intel has now, because of the much faster communication between cores. (Shared cache and, in the case of AMD, also a fast hypertransport link)

And it should also be faster than a 4-processor system (which again have slooow communication between processors because they're physically separated from each others).

If you want an analogy, what's more efficient? Working with 3 others in the same room, where you can talk to each others, help each others out, solve the problems as they appear, or work at separate locations, having to phone/email each others?

Of course it won't make a difference if only one of you has any work to do anyway, but if you're given a task that can actually keep four people busy, you'll notice the difference.

And yes, the Northwood certainly did its job, but it's far from "one of the best CPU's ever". Still a flawed design, and it couldn't keep up with the K8 in any case.

 

I remember really wanting a Northwood at core at one point, towards the end of the AthlonXPs life. I was doing a lot of video encoding at the time and the Northwood ran all over the Barton/Thoroughbred core. Course then Sledgehammer turned up for AMD (still the best codename for a CPU core imo!), and Intel responded with Prescott (snigger).

 

I got a free 3.06Ghz P4 from my friend and am slowly putting together a media center box with it. It works quite well. Hyperthreading does help.

 

Intel's current "quad-core" is like two rooms, with two people in each room, to follow this analogy above.

The AthlonXP was actually a K7. K8 didn't come about until the Athlon64's and later.

I didn't say it didn't work. Look at my sig... those are P4 based Xeon's. The machine's a beast. But it's still not a good processor design overall, because it can't scale much past the 3.6GHz. They can't keep up with an Athlon64 4000+. Even a 3200+ they have trouble catching.

 

Oh yeah, definitely not the greatest pre-Conroe CPU that's ever rolled out of Intel's fabs (1.4Ghz Tualatin PIII, ftw), but it's quite good enough for normal tasks.