i7 620M vs. 720QM

then they should not have stuck in a 720 in that laptop in the first place.
look at the new mbp line, they did not stick a 720m in there cause the knew the design could not afford the added heat.
the same thing also applied to the previous generation of quad cores. aquad will produce more heat than a dual core, thats a given.
most notebook manufacturers put little effort and importance to thermal design. and when new tech come around that requires better heat management, they join the bandwagon, sometimes knowing full well that their systems are not designed to dissipate such heat, and blame the cpu when customers complain.
in the sager, alienware , and asus g73 subforums ive never even once seen a single poster complain about a 720m overheating. im sure there are other notebooks out there with thermal designs just as good . sadly, it seems like your notebook isnt one of them.

 

Did you read what I said? Of course the sager, alienware, and G73 will be fine. Also, it's not that they don't care about heating, you know those people aren't idiots, it's the 720qm.

 

my 620m is delivering.

that is all.

enjoy whatever you decide on, gentlemen.

 

then that just proves its the notebook design that matters.
also, you know the guys at intel arent idiots, its NOT the 720qm

amen to that!

i just fnd it wrong when people blame the cpu
like i said the people in intel arent idiots and a quad core cpu is not for everyone and every notebook

 

Put the i7-620m and the i7-720qm in the same cooling system and the quad will be a lot hotter. The 620m is better because of that difference, and the quad won't perform significantly enough to make up for it.

 

since when was heat a gauge of a cpu's performance?
that really depends on what type of programs you use.
and as multicore aware programs get more and more common the difference will begin to show. and that is why intel is moving to hexa- and octa- cores.
but of course if youre just surfing or chatting on ym or watching [] it would hardly matter...

 

Even if the full processing power was utilized at 100% efficiency (practically impossible), the dual core would not be much slower than the quad core anyway. The dual core turbo boosting both cores would have 89% of the processing power of the quad core turbo boosting all four cores. In any other case, such as where 3, 2, or 1 core is fully loaded, the 620m is quite a bit faster.

720QM turbo boost of:
4 cores: 6.932Ghz
3 cores: 5.2Ghz
2 cores: 4.8Ghz
1 core: 2.8Ghz

620M turbo boost of:
2 cores: 6.132Ghz
1 core: 3.333Ghz

The numbers speak for themselves. The only way a 720QM gets work done faster than a 620M is when all four cores are fully loaded, and even then the difference is not very large.

I really don't see there being much benefit to the 720QM over the 620M, as even these numbers show a best case scenario for the quad core, where all the computational work can be split perfectly between cores.

 

Come on dude, heating is a major factor in going with a CPU for laptops, I didn't say it meant it performs worse.

 

So would the 620M be faster for most applications, everyday tasks, and gaming while having longer battery life and producing less heat?

 

Depends on the situation. I am quite happy with my "slow" 1.6GHz 720QM locked at a range between 0 and 15% of max power and that still eats almost everything I throw at it on daily basis.

Again depends on what you plan to do.
Those "old" C2D eat everyday tasks easily, and most applications too.
Gaming is mostly GPU dependent.
Such a high end CPU is profitable when used.

 

For "everyday" uses, you wouldn't even notice a difference between an i3 vs. i7 since both underclock.

 

Yes. The only advantage to the 720QM vs the 620QM is when all four cores are at full load on the 720QM, but even then it is only about 15% more powerful than the 620M. In all other cases the 620M is faster.

 

true as has been discussed in this thread since jan 2010.
unless your using the 4 cores the 620m will outshine the 720m im most tasks.
but for those like me who do a fair amount of video and sound editing or stuff with a lot of computational factors a quad would be much faster even at 1.6ghz per core.
as explained previously so many months ago, the core nos, ghz and performance is not a linear relationship. also as more everyday programs move to multi core support and efficiency then one may be able to see a significant difference even in day to day tasks ie- browsers are moving to multicore support.
but right now, most every day tasks are easilly performed by a dual core or even a celeron.
with that being said, there is no doubt however that a 620m would perform better in most programs that do not use more than 2 cores, making it a better option to most users ( as i have repeatedly said before) for the time being.

 

heating is indeed a major factor and thats why a laptops thermal design is of utmost importance.
you cant blame a cpu or gpu for overheating unless it happens across ALL models.
if a cpu/gpu is working perfectly in some models and overheating in others then it is clearly the thermal design of the overheating model that is at fault here. its as simple as that.

 

The problem is that everyday programs aren't going to move into quad core support, they are everyday programs. I could see more quad core support for heavier programs, and the quad will be useful if you need to use those programs, but other than that, idts

 

actually many everyday programs are already moving towards multicore(2+) support such as browsers and flash, which you are using right now
with intels push and such its inevitable for almost all programs to move into multicore support just as it was during the single/dual core era. the whole industry wants this because it drives sales with multicore ready apps and multicore pc and laptops.
whether we need this or not in every day tasks however is another story, but the transition will happen.

 

In response to all of the above.

My i7-820QM idles at 42-45C which is much lower than kgh00007's i7-620M, it also maxes out at 71C which again, is much cooler than his i7-620M.

My CPU temps under load were after hours of GTA IV, BFBC2 and World In Conflict gaming. I have an in game OSD and my CPU temps are usually around 60-65C.

So I will repeat what trvelbug said earlier, overheating is often down to laptop chassis design and cooling system and not the CPU.

 

I like the i5 540 better than the 620 or 720. The extra power consumption of the 620 isn't worth the marginal increase in strength over the 540. But that's just because I'm not an avid photo or video editor.

 

ive seen very favorable reviews of this processor across the board.
seems v impressive indeed.

 

Alright, I give up. Not worth explaining what I'm saying anymore, you guys are missing the point.

 

It is more than software just "using" four cores or supporting parallelization. Check this out: http://en.wikipedia.org/wiki/Amdahl's_Law

No tasks on the computer can be completely partitioned out to take perfect advantage of more and more cores. Very quickly we see the limits of scalability, even when comparing dual and quad core processors. With the numbers I came up with for aggregate frequency as a measure of performance, it completely ignored this fact yet still showed that the 620M is within 89% of the performance of the 720QM. Taking into account these problems makes it far worse for the quad. A program that can be 95% parallelized would perform equally on the 620M and 720QM! So it really doesn't matter if software is split into more and more threads, as there are limitations to how far it can be parallelized.

So in conclusion, the 720QM is a piece of trash because even in a theoretical best case scenario it will only beat the 620M by a small margin. Once we look into how well software can possibly be implemented, this slim margin disappears. Everyone who has or likes the 720QM keeps talking about future support for more and more threads as being in favor of the 720QM. But this is a complete fantasy. Games are especially bad because they cannot be parallelized very far at all. In a case such as this, any FPS, past present and future, will run quite a bit better on the 620M than the 720QM, regardless if it is able to offload some of its parallelizable work to other cores.

 

from the same wiki page:

"Danny Hillis (in Pattern on the Stone) has criticized Amdahl's Law as being unnecessarily pessimistic in its assumption that the sequential portion of a program as being 5% (or 50%) of the execution time. In many applications, particularly with very large data sets (such as Google calculating PageRank, or scientific programs doing FEA), the amount of sequential code is closer to 0%, as essentially every data element can be processed independently."

 

And then there are all the programs we as use at home that are horribly bound by having portions that are not parallelizable, the worst offender being games. That part you quote is talking specifically about certain kinds of scientific applications, data mining, and other stuff that most users do not run. Outside of a few examples that pertain little to what any users on this forum would actually do, we run into very real limits to how parallelized a program can become. Anything where there is a linear component to process, even if it is as little as a few percent, shows us drastic issues with the scalability to more cores. Basically anything you can run as a home or business user is going to run into this.

But like I have pointed out, even if a program is perfectly parallelizable and is split into 8 threads, the 720QM can still only be up to almost 13% faster than the 620M. This small boost coupled with the fact that most programs people actually use are limited in how parallelized they can be makes the 620M more powerful across the board.

There is another way to realize the nearly 13% theoretical advantage of the 720QM over the 620M. That would be to run multiple independent programs that each require lots of computational power, enough to load all cores on the processor at 100%. So unzip some enormous files while you encode your music collection into a different format while you play starcraft 2. This isn't exactly a great way to realize the small possible benefits of the 720QM over the 620M.

 

to me it just seems like a matter of programming efficency. those data miners, scientific programs etc are programmed very efficiently and they have shown that you could overcome the theoretical limitations of diminishing returns. when multicore programming and systems becomes maintream we could see this kind of efficiency trickle down to consumer products. thats always how tech works.
however atm ill take the 15% or so increase i get with my video editing program.
with the 720qm being the lowest level i7 quad, its real benefit is the pm55 chipset that allows you to upgrade to the better i7 cpu's later on as prices drop. however if your 620m comes with this chipset too then youre good to go as well.

 

Please do not bash the CPU I am running. As said countless times before, by many users, myself included, the i7 720QM has its advantages depending on each case/utilization. Once the CPU kicks in in full power, the 4 cores and 8 threads available do have an advantage. I run renders on my computer quite often, and I check temps/performance/multipliers/loads all at the same time while running the render. The CPU gets at 100% usage, all 8 threads fully utilized and fully tasked (it even lags the computer haha).

My point is, the 720QM is not "crap" as you say it is, but a more "specialized" CPU, suggested to people who will actually use the full power of it. Even those Pentiums and Celerons run everyday tasks with ease, for most users, the i3s are a lot of power, the i5s are overkill, the i7s even more, and Clarksfield is out of the question. In real life, all high-end CPUs would be "trash" as they run underclocked most of the time. Mine runs at x7 multiplier (931Mhz) and that suffices my daily tasks, I even blocked max performance to 15% for everyday activities, and that is enough.

Not intending to offend, but have you tried both CPUs under everyday activities? (web surfing, word processing, music, etc) Difference is non existent even between my 720QM and the Envy 13's C2D LV CPU...

 

It's not that the 720qm is "crap", it's just that the 620m is a better choice. And for everyday activities, the 720qm's power is meaningless, good point. Another reason the 620m is better overall.

 

Well if the 620M costs €140 more than the 720qm when configuring an m15x (belgian dell site), wouldn't it be more cost efficient to go for the 720qm afterall? (for gaming purposes).

edit: @l3vi, how marginal is the performance increase between the 540m and the 620m?

 

The difference between the 540M and 620M are quite minimal. Depending on cost, typically the 520M or 540M are of best value for their performance.

 

i would get the quad.. after all it is more futureproof and more and more games becomming bad console ports and neeeding more cores and speed , i7 quad would be better...

 

You keep saying this but you never can back up how exactly it's going to be more futureproof. Please read the multithreaded benchmarks which shows the 720QM's performance now, then you will see that even in the future when more programs are multithreaded, it will never exceed the current performance.

 

Has anyone played GTA IV with the i7 620M?

If so, how did it perform?

I find if I disable 2 Cores on my laptop, GTA IV doesn't play as well and stutters but if I enable two logical Cores it performs fine. This leads me to suspect that it may perform well on the i7 620M because of its high clock rate / Turbo Boost and HT capability.

 

Soon there will be a 740QM and a 840QM to throw in the mix.

Notebookcheck: Intel Core i7 840QM Notebook Processor
Notebookcheck: Intel Core i7 740QM Notebook Processor

 

In that case, go with the 720qm. The comparison is really only applicable if they are equal in price anyways.

And all the talk of futureproofing, I think that it's unrealistic. You're going to have the laptop for 3-5 years (hopefully), not 10.

 

What do you mean by disabling two cores and then enabling logical cores? It is like enabling HT in the two remaining functional cores?

And I agree with the futureproof discussion on the 720QM, it is the weakest quad, so it can hardly count as fututeproof in any way.

 

???
ill bet a year and a half from now no one will be talking about two core cpu's anymore.
the only place you prob see them then could be a netbook or an ipad.

 

Well, it is more likely to happen (that nobody talks about dual cores) 1 year after intel releases its lower base models (nowadays the i3) as quad cores.

So far this generation chips are relatively new, but who knows... maybe next year intel decides everything goes quad... but until then, we will see.

 

I will admit, in a desktop I would most likely not buy a dual-core - if I was looking for a budget solution, I'd probably buy a triple- or quad-core offering from AMD - the $75 X3 440 and $100 X4 635 are cheaper than Intel's i3-530, and although they're weaker for applications with few threads, they're better at multithreading. Move the budget higher, and I'd almost certainly buy the Core i5-750. The only exception would be if I was looking for minimum power consumption and good integrated graphics (which I don't see myself doing), in which case I'd still buy a Clarkdale.





However, if you look at the current situation with laptop processors, the gap in clock speed between dual-cores and quad-cores is far larger (as a ratio) than the gap for laptops. The slowest Lynnfield with HT, the i7-860, runs at 2.8GHz (2.93GHz with quad-core Turbo, and 3.33GHz with dual-core Turbo). On the other hand, the fastest Clarkdale, the i5-680, runs at 3.6GHz (3.73GHz with dual-core Turbo). That's a difference of only ~30% in clock speeds, and when the i7 shuts down two cores that difference narrows to only ~10%.

There are other slight architectural differences between Lynnfield and Clarkdale, but they're both Nehalems and for the most part the differences in clock speed and number of cores are a good predictor of how their performance compares. With clock speeds like those, it's obvious that the advantage of quad-core easily outweighs the extra clock speed - in terms of raw power, the i7 offers ~60% more. Since both are ~$300, it would take either ignorance or very specific needs to pick the i5-680 over the i7-860. However, don't unthinkingly take this to mean "quad-core > dual-core" - the situation is more complex than that, as you will see.



Let's look at ~$350 mobile CPUs now, i7-620M vs i7-720QM. Again, both CPUs have HyperThreading, and both are Nehalems. In this case, the i7-720QM has a clock speed of 1.6GHz (1.73GHz quad-core boost, 2.4GHz dual-core Turbo) while the i7-620M has a speed of 2.667GHz (3.067GHz dual-core Turbo). Now the difference is ~70% in clock speeds, down to ~30% with the i7 on two cores.

For the laptop CPUs, then, the i7-720QM has an advantage of only 13% in raw power, which is far less than the advantage in desktop CPUs. Even if your software makes completely full use of the power of both CPUs (as benchmarks show, it will not), you will still barely see the performance difference between them; you're more likely to notice the i7-620M's advantage in single-threaded performance.





So, back to the question at hand - in desktops, dual-cores are aging, and I see little reason to buy one now. However, the situation is clearly very different in laptops, and I would assume that this is primarily because of limitations on power consumption. I think dual-core will still be the better choice for most people in a laptop until 2012, when Intel's 22nm Ivy Bridge hits, if not later. I've read that Ivy Bridge will bring quad-core to Intel's entry level, though this probably applies to desktops.

Nonetheless, it's mostly irrelevant that quad-cores will be the standard a few years down the road - even if almost all applications are multithreaded at the time, the i7-620M will perform pretty much the same as the i7-720QM on average. Since you're buying a CPU for performance, and not just performance three years from now but at every time in between, you should still get the i7-620M now because it will be faster overall for quite some time yet, with lower power consumption and generally a lower price. The only kind of futureproofing the i7-720QM will get you is that people won't laugh at you for having a dual-core - though they will laugh anyway after they hear you've got an i7-720QM.

In any case, the real winners are the Core i5-520M, the i5-430M, and even the i3s - they still offer great performance, and they cost a lot less.

 

Yes, I mean enabling HT on the two physical Cores. The HT are often referred to as logical Cores.

 

No, its not. Logical cores are the cores seen by the OS. You can't differentiate between the ones shown when you have HT disabled and then the ones shown when HT is enabled. They are all logical cores whether we see 12 from an i7-980X or one from an Athlon XP. All we know is that with HT enabled, 2 logical cores correspond to a single physical core.

It's hard to figure out what you are talking about. So you had HT disabled and the four cores running, then you disabled two of those cores and it doesn't run well, and then you enabled HT with still only two cores, and then it started running well again?

 

Thanks Trottel, that is precisely my confussion with his post. I thought disabling 2 cores would not matter for HT. Or is that in some chipsets HT is disabled??

 

Windows Taskmanager will show 8 Cores but I use a different Task manager which clearly shows which Cores are logical and which are physical and they are labeled Core 1, Hyper Thread 1, Core 2, Hyper Thread 2. This allows me to chose Cores without accidentally selecting a logical Core instead of a physical.

This is what I mean when I mention disabling Hyper Threading i.e selecting the affinity of the physical Core and not the logical one. I was simply following how the program labels the Cores but I forget, unless you are using the actual program (Bill 2's Process Manager), it does not make much sense,

I don't mean disabling Hyperthreading overall as you may do from the Bios.

So when I tested GTA IV, I noticed bad performance if it was using 2 physical Cores but enabling 2 logical Cores alongside this, performance was almost as good as 4 physical Cores.

 

Did you check your temps,before and after disabling Hyper Threading(so to speak)? Am curious to know, how much of a diff. in temps it will make.

 

That doesn't make a whole lot of sense. I doubt you would have the same results had you actually disabled/enabled cores and hyperthreading. In some cases, up to a 30% performance increase can be realized by enabling HT. Games are not these cases. The performance difference in games is usually +/- 5%. Yes, that is a minus. It also sounds like there was a much greater performance increase when you went from selecting only CPU 1 and 2 to the same with HT 1 and 2 also enabled than could possibly be realized by HT under the best of conditions.

Also just because it labels cores a certain way doesn't mean anything. They are all logical cores and there is no difference between sending a process to "Core 1" and "Hyperthread 1" as it will be done the exact same way on the exact same core. I think its there just to show which two logical cores pair up to each physical core. There is no real cpu and then the virtual cpu. They are identical.

 

Whats the difference from a logical core vs. physical core? Do physical cores have more processing power then logical cores? So from what i've read...logical cores include physical and virtual cores.

 

@ Throttel

I see exactly what you mean now, thanks for the detailed response.

I am really curios as to how the mobile i7-620M will perform in GTA IV so if anyone has any ideas, theories or real facts as to how it will perform, feel free to share. I know GTA IV is better suited to Quad Cores but I hear some have good results with higher clocked Dual and the i7-620M has a decent Turbo Boost.

The reason why I ask is because a friend of mine is interested in that CPU for emulation but also wants to carry on playing GTA IV. All of their emulators favours a high clock rate and 2 Cores so the mobile i7 Quad loses out a little.

 

The physical core is the hardware, the virtual core is the "software". Each hardware core has two "software" cores. Core 0 appears as C0 and C1, either way you choose to work on C0 or C1 you'll end up with the same performance.

When using TB, normally the C0 will have preference over C1 and shut down C1 to overclock C0. But on regular basis, when TB is not needed, both C0 and C1 work the same way.

 

I wouldn't really call HT software, since it does require additional hardware. The best way to look at it is that it creates two virtual/logical cores for each physical core. In other words, if we have logical cores 0 and 1 corresponding to physical core 0, and logical cores 2 and 3 corresponding to physical core 1, setting an affinity for logical cores 0 and 2 should be the same as setting an affinity for cores 1 and 3.

GTA IV is very CPU-heavy and capable of using 4 cores, but that doesn't mean it uses 4 cores all that efficiently. Consider this benchmark - although it shows that GTA IV can use 4 cores, the 2.4GHz Q6600 only achieves the performance of a 3.6GHz dual-core (slightly worse, in fact). With that in mind, quad-cores only have a ~50% advantage over dual-cores at the same clock speed, which suggests to me that the i7-720QM will only perform as well as a 2.6GHz clocked dual-core, and so the i7-620M would likely get better framerates.

 

Oh, so HT apparently accelerates parallel computing because it allows programs to use more logical cores then there are physical cores? So in away when HT works, the clock speed and power of one physical core is cut in 1/2 for one virtual core.

 

HT: Think Lego pieces of instructions to the core being neatly fitted together.

 

Not quite. If you only had two logical cores with half the power of the original, it wouldn't be worth it in the first place. In that situation, there is no real advantage to multithreading - it would be no different from just having each thread use the CPU for half the time, and that's how every CPU without Hyper-Threading works.

What you have to understand is that even when you're just running one thread, the CPU can execute more than one instruction at any given time - the CPU has a number of execution units, and can in fact use more than one of them at once. This is called superscalar architecture.

However, when using these resources for just one thread, it may be the case that you can only use perhaps one or two at once due to the structure of the code. In this situation, Hyper-Threading allows a second thread to use some of the execution units that aren't being used by the first. This is the reason why Hyper-Threading with two threads can be faster than just using one thread for each physical core. Without HT, each thread would take turns using the CPU, and because of the overhead of switching performance would in fact be slower.

Nonetheless, the advantages of HT depend heavily on how the code is structured. The advantage offered depends on the application, and can vary from slight decreases in performance to ~30% increases.