How do you evaluate a processor?

simple question, what do u have to know to judge a processor


One sub question: Intel® Core™ i7-820QM Processor VS Intel® Core™ i7-620M Processor

thanks in advance

* i mean what magnitude should be considered to infer that this processor is better than that processor

for eg: this box is better than that box because it more VOLUME... that way
thanks

 

http://www.notebookcheck.net/Mobile-Processors-Benchmarklist.2436.0.html

 

We need to know what you'll be using the processor for to give you a useful answer.

In an overall sense, the quad-core 820QM is faster, but you'll only benefit if you're doing heavily multithreaded work, so the extra cost might not be justified.

 

* i mean what magnitude (or number) should be considered to infer that this processor is better than that processor

for eg: this box is better than that box because it more VOLUME... that way

about the second answer, can i ask y, because the 620M had more ghz, till 3.33 but 820QM has only till 3.03

 

more GFLOPS? <asdfgdsad>

 

Sorry, no idea what you are trying to say. What do you mean by "VOLUME"?

The only accurate way to judge if a processor is better for your requirements is to benchmark it running the applications that are important for you. In simple words, try out the systems you are interested in, and then decide whether the differences in performance, if any, are worth the price differential. There's no simple answers otherwise.

P.S.: It just occured to me that when you were talking about boxes, maybe you simply referred to containers to put stuff in. If so, notice that even for simple boxes, the answer is not as simple as that. A box can be "better" than another one because it is more sturdy, more lightweight, better form factor, easier to carry, etc., etc.

 

Ah, but different boxes are for different purposes, so even for boxes, bigger isn't better. It's similarly so for CPUs - which is better will depend on what you want to use it for.

 

Yes, similarly even processors have different features like no of threads, cores, ghz. what other things?

what i want to ask is, there are 2 processors one with 2 cores and one with 4 cores, so the quad core is better (here, no of cores is a feature) similarly, what other features should i consider?

irrespective of what im gonna use it for, one will always have more potential than the other, right? that's what im trying to figure out. the processor with the optimum potential within my budget.

thanks for the quick reply, btw

Yes, similarly even processors have different features like no of threads, cores, ghz. what other things?

what i want to ask is, there are 2 processors one with 2 cores and one with 4 cores, so the quad core is better (here, no of cores is a feature) similarly, what other features should i consider?

irrespective of what im gonna use it for, one will always have more potential than the other, right? that's what im trying to figure out. the processor with the optimum potential within my budget.

( i know i posted the same reply to both, i just wanted you to know i replied)

 

Wrong. While on paper on processor may be better in terms of specs, how the processor will perform in actual real life situations will differ. You know why? Because the actual hardware is only half the story in computing. The other half is software and HOW a software is coded will affect its performance on a given set of hardware.

For example, not all applications are multithreaded so number of threads is only half the story.

So no, processor performance can rarely be irrespective of your uses. Potential is nice, but it still relates to your uses.

If you want to know all the components to compare processors in terms of specs, they are:
- clock frequency
- amount of cores
- the presence or not of things like hyperthreading and turboboost
- amount of cache

 

Alright i get it.

i did read a bit on wiki but im not very clear what are threads and heyperthreading. what is it?

and how is cache measured? more the better or less?

Thanks for that info!

 

Actually yes, irrespective of its use, one processor will always have more computing power than another. The worst that can happen is that the actual performance difference in a single application is negligible between two different processors, not that either one will perform better than the other depending on the situation.

While this is fine for processors using the same core, these sorts of quantitative measurements fall flat when comparing different architectures and don't tell the whole story even between different revisions/generations of the same architecture.

 

I agree with Trottel. CPU processing power can be determined to between different CPUs, which is what the OP calls "potential" I think.

However, CPU comparing is not a simple 1-to-1 measurement really. The total processing ability of a CPU is determined by multiple factors which actually change with architectural differences.

At the end of the day, I think the OP just wants to buy the best he can afford CPU-wise regardless of what his uses are.

 

i do have a little idea about comparision w/ diff cores,
well if what i heard is correct, number of cores multiplied by ghz can help in comparing two processors with diff. no. of cores

 

Don't base your choice on clock speed, this already happened with people who bough Pentium 4's, we don't need it on these processors as well.

 

Really agree with u... my pentium 4 system felt way slower compared to my core 2 system... even though the pentium 4 processor was 3.4GHz... also ur better off buying 820QM as
Its a quad and with more applications/ games becomming multi-threaded , the 8 "cores" in it will help. Also u have better future-proofing if u buy 820qm as quads become standard...

 

a) does it work
b) can I afford it

 

That's just not true. While CPU architecture has been improving, performance has not improved in all areas equally.

For example, according to AnandTech's Core first Core i7 review,

Sure, you could say that Nehalem is superior to Penryn, which is true, but those aren't processors, those are architectures. If you look at the specific benchmarks, if you compare the i7-920 against the QX9770, for example, you'll find that in some situations the i7-920 wins by a big margin, but in some it loses heavily. Simply looking at the numbers, you would expect that if a Penryn would vary between 15% faster and 20% slower than a Nehalem that was clocked at 20% slower than the Penryn.

Similarly so, the situation isn't so simple when we're comparing dual-cores against quad-cores, even when both are using the same architecture. Sure, a quad-core is better overall than a dual-core at the same clock speed, but dual-cores are generally clocked faster than quad-cores. In applications with no multithreading, a quad-core will perform the same as a dual-core. In most games, where multithreading can only go so far, you'll get 50% more performance or so from a quad. In 3D rendering and video encoding, a quad-core is almost twice as fast as a dual-core. (All of this is assuming the quad-core has the same clock speeds as the dual-core).

Intel's Turbo Boost has turned things more in favour of quad-cores, since now the quad-cores can operate as reasonably fast dual-cores as well. However, when we look at mobile quad-cores, the clock speed difference between quad and dual is very large, so when you compare, say, the i7-540M agasint the i7-720QM, you'll find that one or the other will have the advantage, depending on the situation.

If you look at this thread, the i7-620M beats the i7-720QM overall, for example.

 

Great, it does work for me considering the budget and other compatible specs, BUT , shouldn't we consider where gaming software technology is heading?

aren't they advancing towards quad cores with higher cloclkspeed (this might be a noob talking) but a lil research i did, about sys req. of the latest games did give me that idea ? and don't u think more softwares in the future, will have multithreading?

(i have to make do with this laptop for.. roughly 7 yrs) i don't want it to get outdated in first 5 atleast!

I'm not sure how imp this is, but i do a lot of video editing, and i have Sony Vegas 9 and am gonna get MacroMedia Flash soon, but i dont think its 3d animation.

 

The second you buy your computer you're outdated dear

Some purchases are more future-proof than others, but it always relates to what you ARE doing what you PLAN on doing.

For example, if I have no intention whatsoever to do anything but email and MS Office, it's of little use to me to future-proof all that much because those applications will advance, but not to the point of requiring massive hardware to run.

If you're into gaming, your graphics should be your first priority. CPUs, while still being important, do not need to be of higher tier as much as graphics do for most games(Flight Simulators and RTS games being the main exceptions).

For video editing, it's usually CPU bound, but how demanding that is depends on mostly how high res your videos are, what effects you put, what kind of encoding and all that jazz. Video Editing runs on dual cores, just that it might be faster on a quad depending on what you do.

 

No games out there are properly coded even for 4 threads, this isn't going to improve much in the future. The general consensus among processor architects is they will stop increasing amount of cores soon in the future, probably sometime in 2015 with 10 cores for PC and go for heterogenous cores.

You can keep increasing for servers, but for PC, there's an absolute limit. They can go for hybrid CPU combo where you'd have small, many cores combined with fewer large cores and satisfy both. For Intel, that's probably where Larrabee comes in. When they integrate a future Larrabee-derivative, they can run parallel apps on the mini cores on the Larrabee and run single thread apps on the bigger cores.

This also points out how hard it is to quantify CPU performance. It's like asking which is a better automobile? A car or a truck? It depends on what you do of course.

 

well said

well then which processor do u suggest for gaming (till 5 yrs in future, at least 3) some video editing, and some encoding?

whats ur take on i7 720QM
Cores - 4
threads - 8
6 mb cache
1.6-2.8 ghz

and i7 620M

cores - 2
threads - 4
2.66-3.33 ghz
cache - 4mb

the price diff is only 32$, 720qm being costlier

So do u mean the gaming software technology will take time to catch up with the hardware?
may i ask u this? what did YOU consider in your CPU while chosing it? and what are u using it for, right now?

So do u mean the gaming software technology will take time to catch up with the hardware?
may i ask u this? what did YOU consider in your CPU while chosing it? What are YOU using it for?

 

for the price difference , get the 720qm!

 

how would u interprete this from rookie language to technical detailed language?

CPU REQ for Saboteur
Core 2 Quad Q6850 3.0GHz
(another site Quad Core running at 2.8 GHz or equivalent


CPU REQ for GTA IV
Intel Core 2 Quad 2.4Ghz


Now, you may think this topic doesn't belong here, but i'm just trying to find out, when they only give the ghz of a cpu in sys req, what do they actually mean?

 

Get the 620M, 720QM is not worth it, especially if the price is a bit higher too. There's no practical situations that will have 720QM faster: http://forum.notebookreview.com/showthread.php?t=455347&highlight=i7+620M

 

It's more complicated than just "software technology". The thing is that video games, in their very nature, have a lot of sequential bottlenecks. As a consequence, there is only so much you can do to parallelize most video games.

 

I don't see that.

 

The most notable one is that video games are real-time, and so everything needs to be synchronized.

 

The reason that its hard to parallelize is because ever since GPUs started offloading most of graphical effects from the CPU, it stopped having a main source of very parallel code-graphics.

When you wish to push pixels, you can basically not worry about anything else and make something parallel to process them faster.

The CPU in a game basically deals with driver management, physics, sound, and AI.

Say for example, how will you use multiple cores to make a pathfinding algorithm better? Or calculate which part of the broken vehicle is going to fall where? The dynamic environment that is required makes it hard to parallelize as the CPU needs to adjust to whatever its being thrown at any time.

For pixels, its easier as most do not change dynamically like physics and sound does and the processing problem is mostly pixel pushing power.

 

i'm sorry i didnt get that.
i googled sequential bottlenecks, though i didn't get anything
and what do u mean by 'parallelize' ?

can u please respond to comment #25 also?

i wanna ask you, what made u chose that?

 

for multi-thread real-time data streaming apps i think 720QM is still better than 620.

 

sorry again but, 'real-time' and 'synchronised' ?

 

By sequential bottlenecks, what I mean is tasks that must be done one after the another and cannot be done in parallel. Parallelization is the work of spreading the workload of a program over multiple threads that can be run simultaneously.

IntelUser gave some detail on what I was getting at:

Despite this, there are some tasks that are inherently parallel; processing video is the foremost example of such a task. If you look at benchmarks for these kinds of tasks, this is where you'll see quad-cores dominating dual-cores. However, as IntelUser has said, this is precisely why GPUs were made in the first place. GPUs are enormously parallel - AMD's HD 5870 (the desktop card) has 1600 stream processors. The only reason GPUs haven't entirely replaced CPUs in these tasks is the fact that GPUs are very specialised devices, while CPUs are very much general-purpose. For these kinds of tasks (e.g. 3D rendering and video encoding), GPU acceleration is the future; it's just that CUDA and ATI Stream aren't widespread enough yet.

That isn't to say multi-core CPUs are a dead end; clock speeds can only go so high, and there's plenty of situations where a quad-core will still be, say, 50% faster than a dual-core at the same clock speeds. However, power and heat limitations force quad-cores to run at lower clock speeds. Intel deserves a lot of credit for the advent of Lynnfield; its newly improved Turbo Boost essentially combines the advantages of quad-core and dual-core CPUs into one package. The i7-860, for example, is, factoring in Turbo Boost, effectively a 2.933GHz quad-core and a 3.2GHz dual-core mixed into one package.

However, Clarksfield (mobile Core i7), the mobile version of Lynnfield, doesn't have this level of success, especially not the i7-720QM. This is simply because its frequency is too low when running on four cores. If you compare mobile CPUs to desktop CPUs, the i7-720QM is only ~60% as fast as the desktop i7-860 (the slowest Lynnfield i7), while the i5-520M is 75% as fast as the desktop i5-670 (the fastest Clarkdale).

 

So do you mean to say, the mobile processors are really backwards as compared to desktop processors?

BUT, how would you rate i7 720QM compared with other mobile processors?


BTW, please respond to comment # 25, please. that will make a lot of things clear to me.

 

It means that, for that generation (Core 2, in this case), that's the GHz your processor needs to be rated at to run. I'll note, by the way, that those numbers are the recommended requirements, not the minimum, so you can actually run those games with a CPU rated lower than what they say. You need to be looking at minimum requirements to know what the very lowest (they say) you can get away with.

Also note that the number will change as you shift generations; due to the advancements in processor technology, the Core i series will require different numbers than the Core 2 generation. For example, it's quite possible that (just tossing out a random example here) a dual-core Core i running at 2.5 GHz will be the equal of a Core 2 quad-core running at 2.4 GHz, thanks to the new architechture and Hyper-Threading.

And yes, mobile processors are nowhere near as good as desktop processors; this is only natural, considering the disadvantages they have compared to their desktop brothers (they need to run on lower power, they can't run as hot, they need to occupy less space). It's like comparing, oh, a Toyota Prius to a Ford F-150 truck. The Prius will be more efficient, and use less gas, but the F-150 will massively outpower the Prius in sheer horsepower, load capacity, and probably general usefulness.

 

Mobile processors are always slower than desktop processors; this is an inevitable result of the need for lower power/heat. The thing is, heat/power is even more of a problem for quad-core CPUs, and this is what brings mobile quad-cores down - while that amount of power is good enough to run two cores pretty quickly, you have to slow quad-cores down a lot to get them to run at 45W.

For example, there is no doubt that the Core i7-920XM is the fastest consumer mobile processor in existence. However, it uses 55W of power and costs ~$1054 (Note: I'm going by the prices listed on Wikipedia). The i7-820QM is probably the second-fastest, but it's a $546 part.

The i7-720QM is a good CPU, but if you look here, you'll see that the i7-620M is a better CPU overall. In addition to this, the i7-720QM uses 45W vs 35W, and costs $364 vs $332. On the other hand, the i5-540M and i5-520M are a little slower in an overall sense than the i7-720QM, but they're much cheaper, and likely to be faster in situations where only 1 or 2 cores would be used. My personal choice of mobile CPU is the Core i5s (or even the i3s) based on value for money, and 35W power usage. If you have more money to spend, you could go with an i7, of course.


As for your question (#25) on video game requirements, the problem is that they simply don't give you enough information to work out what performance will be like for various components.

Basically, here's what I take out of the system requirements for GTA IV and Saboteur:
"This game is a terrible console port; we haven't optimised it for PCs at all, so don't expect it to run particularly well, even on your high-end system."
Without benchmarks, there's not much else to be said.

 

They say that both the games require quad core, 620m isn't quad core though?
what is 2.4 quad core equivalent in core duo?

Oh yeah, i'm having a tough time interpreting Sherly's thread.

 

Ok, let's put it in simple, crude analogies ok? The following is far from perfect, but it's a "in a nutshell" type of analogy so it doesn't need to represent a CPU perfectly.

Say a CPU is a group of students working on a project.
1- number of cores = number of students in the group
2- clock speed (GHz) = how fast each student can work (ex: they can write 1 page/minute)
3- threads = parts of the project (ex: research, development etc.)

Now, the whole purpose of multi core and threading is to divide the work done. Let's take the above example with the students. I have a project. Sure, one student working very very fast on Redbull(say 3 pages/minute) can achieve the same amount of work as 3 slower students(say 1 page/minute each), but it's not an efficient way of working.

This is why there are threads. The purpose is to separate the project into "parts"(i.e. threads) which each student can work on individually in parallel so as to achieve more work in a same amount of time whereas a single fast student couldn't. Now, the issue programmers have when making a program which is "multi-threaded" is to make each thread non-dependent on each other. Translate this into the project example. If student 1 is doing research, student 2 cannot write the report without student 1 finishing his job right? This is called "dependent threads" i.e. where one thread depends on another to do its work. Just as student 2 cannot undertake his task without student 1 finishing, dependent threads defeat the purpose of multi-threading and multi-cores. So really, a proper multi-threaded application would make threads which are not totally dependent so that each core can undertake one thread without having to wait after another core. For example, you could split the research into parts for the students to each do.

Now, what's special about the Core i family, which doesn't translate into the student example is 2 things: Hyperthreading and Turboboost.

Hyperthreading allows in a nutshell, the use of what most people call "virtual" cores by allow each core of the CPU to actively use 2 threads each This means that a dual core i5/i7 can theoretically use up to 4 threads at the same time, making it a "pseudo-quad core". The real quad core i7(the 720QM and up) can use up to 8 threads, but as a consequence of their power use and heat use, they were clocked considerably lower than the average CPUs we consumers are used to, which in turn gimps their potential quite a bit(as some developers still do code with maximum clockspeed in mind).

Now, Turboboost is simply a function which allows Core i CPUs to adjust their clockspeeds depending on what task they're doing. If a CPU isn't being used to its fullest, why bother running it to its fullest right? If a project only requires 1 student's workload, why have the other 3 come over? You don't, you send them home. In the same sense of thinking, Turboboost will actively "shut down", increase and decrease core clockspeed depending on what task it is given.

Now, to go back to your games, those system requirements ask for a 2.4GHz Quad Core. Now the question I'm asking is does it say "quad core" or "core 2 quad"? Because quad core designates a CPU with 4 cores while "Core 2 Quad" is a family of Intel CPUs which are quad core. Yes, there is a distinction. A "2.4GHz quad core" could mean ANY quad core clocked at 2.4GHz, be it an Intel Core 2 Quad, an AMD Phenom, an Intel Core i7 or whatnot and obviously, the importance and efficiency of clockspeed changes with each CPU architecture(one CPU might do more work for a same clockspeed as another).

 

Whoah! Great answer.
suddenly a lot makes sense!

Thanks for ALL that info.
appreceated!

Just this question,

clockspeed solely doesn't describe a processor, right? like the 4 in 4 GB DDR3 ram, pretty much describes everything in there (except for the 3 in ddr).

some processors will work better than others at the same clock speed, is this true?

clockspeed only describes how much a processor IS working in comparision to itself and its potential, right?

 

Yes, this is where architectural generation comes in. Within the same generation of processors (such as the Core 2 generation, the Core i generation, or the *shudder* Mobile Pentium 4 generation), you can compare clockspeeds almost globally; a 3 GHz processor will run twice as fast and process about twice as much as a 1.5 GHz processor when both are running at full capacity. Where clockspeed fails is when you cross generations, such as when you go from the Core 2 generation to the Core i generation. Due to advancements in technology, the Core i generation simply gets more done for each tick of the clock. This means that a Core i CPU will get more done, and thus be faster, than a Core 2 CPU rated at the same clockspeed, even before you take into account Hyper-Threading and Turbo-Boost.

 

Thanks! exactly the answer i was looking for!

Is it true Intel Core i9 processors will be releasing later this year with 6 cores?

 

The problem with calling hyperthreading making it a pseudo quad core is that hyperthreading doesn't increase the computing power of the processor at all. It simply lets a second thread take over in case the first one can't be executed, thereby more efficiently using the same processing power available.

 

Yes the desktop is... for mobile , it will be 2011...

 

Like.... Cinebench which the 620M is faster already? Will you sacrifice performance in every other app for that 1 app that might or might not exist?

Hyperthreading, or Simultaneous Multi-Threading is there to increase utilization of the otherwise idle execution units. They can switch threads to execute faster but the primary purpose is higher utilization by filling empty "bubbles" in the pipeline.

So yes, you can call it "pseudo-quad."

There is a specific name for the type of multi-threading you are talking about. It's called SoEMT or Switch-on-Event Multi-threading. When it encounters a high latency situation, it can switch threads. The Itanium 91xx series uses SoEMT. Because it doesn't increase utilization in any direct way, the benefits are significantly less.

 

Lol, isn't that what I said, though not quite as eloquently?

The way Forever_Melody put it made it sound like you get the benefits of having two cores in one, but hyperthreading may or may not provide much benefit depending on the situation and will never give the same benefits of having two actual cores. I'm not trying to bash hyperthreading but sometimes it is made out to sound like it is a lot more than what it really is.

 

Hey, I did say that it was "in a nutshell" , hyperthreading definitely does not yield the full advantages of an actual extra core. The word "pseudo" IMO kinda led on that it wasn't actually emulating an extra core. I was just trying to put it in the most blunt and stupid simple term I could.

 

i have 21-40 threads of real-time data streaming apps running, each of them could be cpu demanding at some point or at same time for a while, hence i prefer as much hyperthreading as possible from cpu, so that i have much less chance to get frozen. as such, i guess it's better for me to go with 720.

 

Thanks a lot, you guys!
I know what i want and what's better and what's bad.
This Forum is great!

 

ok wait
i'm back here

with asus g73, is it a safe bet buying 720qm?
while everything is considerably future proof, should i get 720qm or some other processor?

i mean it in a hypothetical sense. idt i can afford a g73

 

i7-720qm is one of the best mobile processors.. so it is safe to get it.. for ur budget u can't get anything more.

 

even with the new i7 *40QM series and the extreme 920xm processor?
in i7, 720qm is almost entry level, barring 620qm, right? and there are about 4-5 more in the series.

my curiosity only grew becuase i saw a threads on xoticpc forums saying this...