Desktop replacement: dual or quad core?

I am planning to buy a new laptop this weekend, and I want a desktop replacement - just tired of small screens and low performance, and, unfortunately, I simply do not have a desk to put a high-end desktop. If I was to buy a desktop, it would certainly be equipped with a Core i7-860 2.8 GHz processor. While I cannot replicate such power in a notebook, I am trapped in a dilemma of choosing between four cores or a high clock speed. In a desktop, it seems to me that such dilemma does not exist, since the processors can use more power and have higher clock speeds: it would be worth more to have a 2.66 GHz or a 2.8 GHz four-core than a 3.2 GHz or a 3.33 GHz dual-core. But in laptops, it's a completely different story.

The contenders are basically the Core i7-620m and the Core i7-720QM (or the i7-740QM), and the runner-up is the Core i7-820QM (and i7-840QM), if it is really worth it.

I have done extensive research on the Internet. The sources are not many, but it led to to some conclusions.

The Core i7-720QM 1.6 GHz has 4 cores and 8 threads, but a low clock speed (1.6 GHz) that can be increased up to 1.73 GHz with all cores operating. It can go as high as 2.4 GHz with only two cores. The Core i7-620M, on the other hand, has a clock speed of 2.66 GHz, which can be increased up to 3.06 GHz with Turbo Boost using all cores.

Theoretically, the i7-720QM would be a superior processor. Intel has put a higher number to identify it (7 instead of 6... duh...). Four cores operating at 1.6 GHz equals to 6.4 GHz (in the case of i7-720QM), while two cores operating at 2.66 GHz equals to only 5.33 GHz (in the case of 620M); with Turbo Boost, the i7-720QM would sum it up to 6.92 GHz and the i7-620M to 6.12 GHz - still a big gap in performance. In addition, the i7-720QM has 6 MB L3 cache while the i7-620M has 4 MB. But that's just theory. In real life, things are a little bit different.

I do have a Core 2 Duo right now and I see Windows making extensive use of the two cores. However, I suspect that even the most advanced software are not 100% optimized for multi-core and multi-threading processing. A clock speed of 1.6 GHz could be a disadvantage in this scenario, especially comparing to the much higher clock speed of the i7-620M. The i7-620M has a clock speed which may be 1.33 GHz higher than the Core i7-720QM, and that seems to me a big difference.

I've read that the i7-620M would be better for single-threaded or lightly multi-threaded applications, due to its higher clock speed. Some sources say that the i7-720QM would be the better choice for heavily multi-threaded apps, while others say that, due to the huge difference in clock speed, the i7-620M would be the winner even in those cases.

There are other factors which must be taken into consideration, of course. The i7-720QM has 6 MB of L3 cache, while the i7-620M has only 4 MB, and that makes a difference - however, I do not know whether this additional 2 MB make it up for the huge gap in clock speed. The i7-720QM also supports 1333 MHz memory, while the i7-620M supports only 1066 MHz memory, and I do not know how this will affect the performance - some sources even say this is irrelevant.

The i7-620M is a 32nm, 35W, processor, and consumes less power than the 45nm, 45W, i7-720QM. It means less heat and more battery life, of course. But, in terms of performance, less heat and less power consumption could mean that the i7-620M could achieve its top Turbo Boost performance more easily than the i7-720QM. As a result, it would be more likely for the less-power hungry i7-620M to achieve the 3.06 GHz Turbo Boost performance than the i7-720QM to achieve the 1.73 GHz.

I've seem some benchmarks on the Internet. In Passmark Software's website, the Core i7-720QM scores higher than the i7-620M, but I am afraid these numbers reflect a theoretical performance that nobody will ever get to achieve in day-to-day situations. Notebookcheck has done some comparison too and it ranks the i7-620M in a higher position than the i7-720QM. The i7-720QM scored higher than the i7-620M in most tests, but Notebookcheck thought the i7-620M would be a superior processor - perhaps it thought the i7-620M would be faster in real-life situations.

I have not yet come to a conclusion. I am leaning towards the i7-620M, as it would be a faster processor than the i7-720QM in most situations. I suspect I do not use very multi-threaded applications; however, I do extensive use of multi-tasking. It is very often to me to keep Microsoft Office applications, a web browser, a multimedia player, Adobe Reader and other applications opened simultaneosly. And I like them all to run very fast all the time...

Now that I have done this research and that I still can't reach a conclusion, I would like some help. Are the conclusions I came up with (above) correct? Which of these processors would be faster and which one would be the better choice? And how these processors would compare to mine (a Core 2 Duo T8300 2.4 GHz)? Thank you for the help!

 

My that's a massive long thread that sounds like you're caught in a paradox. To make things simple, Intel has already stated that the future of CPU development is in multi-core design not clock speed. The only hold back at the moment is software development that can optimize it.

If you want the best bang for your money for right now, then get the fastest CPU you can find. However, if you have an application that can utilize a multi-core processor, that will be a better investment.

 

Thank you for the answer.

Intel stated that the future of CPU development is multi-core and not clock speed because it just cannot reach higher clock speeds than 4 GHz. However, we frequently see Intel updating its chips to offer more GHz per core. We have no idea of what the future will be, however, as graphene chips may replace silicon to increase clock speeds up to 500 GHz.

But, anyway, I don't think I should buy a computer thinking of a future that may well change its course. I am planning to buy a new laptop right now, and in two years it will probably be replaced by some other computer. So, when you say the best bang for my money right now by choosing the fastest CPU, do you mean the 2-core i7-620M or the 4-core i7-720QM?

 

Between those two, get the i7-620M. Most of the time the 620M is faster.

 

If you can, wait for the 740QM as it turboboosts the same speeds as the 620 and is cheaper than the 820. But if you're looking for one now and don't do stuff like video encoding go for the 620.

 

Thank you, that's what I was suspecting...

The i7-740QM reaches 2.53 GHz in TurboBoost Mode with 2 cores operating, and 1.86 GHz with 4 cores. It's basically the same as the i7-720QM, but 133 MHz faster. The i7-820QM has 8 Mb of cache L3, while the i7-740QM has 6 MB, so I assume the i7-820QM will be a little bit faster.

I may do some video conversion to use some videos I have on my iPod. Would a 4-core i7-720QM/i7-740QM/i7-820QM be faster than a i7-620M for this purpose? I guess it will depend on the software I'll be running and on its optimization to use parallel processing, right?

 

Don't forget HT capabilities of Intel's mobile i-series CPU. HT gives a big boost for tasks that can use as many cores as possible.

 

Yes, that's true. However, both i7s have HT (4 threads for the dual core i7-620M and 8 threads for the i7-720QM) - I am afraid that HT will not make the difference between them...

 

Yes, the quad cores would be faster. But transcoding to that small of a resolution isn't going to be a huge deal in general.

Another question to ask yourself... do you ever expect use your laptop on battery for very long? If so, you should really not consider a quad core. They run hotter and use much more power.

BTW, when you added the GHz together in your initial post? Completely worthless. You can't do that because there are so many other factors in the performance than just the raw clock speed, including the memory bandwidth and the cache hits and misses and such.

The absolute biggest question is: What will you be doing with your machine? Gaming? Transcoding movies? Image editing? Light web surfing? If you're just gaming and otherwise just have "normal" use, go with the 620M, or even better the 540M. More bang for your buck. If you will be running CPU-heavy, highly threaded apps, then a quad-core isn't a bad idea. A difference between 2.4GHz and 3GHz isn't going to be huge in almost any usage scenario (up to 20% difference at the VERY most, and that's assuming the bottleneck is purely CPU speed and not memory or the hard drive, which are MUCH more likely). A difference between 2 and 4 cores can be double, if it's a well-threaded application.

Main gist: I would recommend the 540M/620M anyone that wants performance and anything resembling portability (best value for the dollar is the 540M), and a 720QM or any other quad core for those who want performance at the expense of power and heat. Stop worrying about the clock speeds so much... the 720QM is a very, very fast chip, and the 820/840's are even faster.

 

Thank you. I am not really worried about battery or portability in this case. This one will be a desktop replacement and I want the best performance I can find. I already have a thin and portable laptop to carry around, I'm just buying this one because I have no place to put a desktop.

I know that a 4-core CPU is supposed to be much faster than a 2-core. However, the clock difference between a i7-620M and a i7-720QM is more than 1 GHz, and I found some conflicting information on the Internet (this benchmark here, for instance, compares an i7-620M and an i7-720QM with the same configuration and found the i7-620M to be the faster one: Intel Mobile i7-620M vs i7-720QM Benchmark.

I know that the added GHz is worthless, and that's my point: there are so many factors that may affect performance (multiple cores, clock speed, memory controller, cache, software optimization) and that's why I could not figure out which one would be better.

As for my usage, I use "normal" software, but I do use them to the extreme sometimes. Think, for instance, of a 500-page Word document with over 1,000 footnotes and 3,000 Ednote citations, each one updating automatically as I change any of them - this I found to be a very demanding task, and a high-end Core 2 simply could not handle it without serious slowdowns.

 

If one uses his pc for encoding and rendering purposes, 4 threads vs 8 threads will make a world of difference.

But if one's just gaming or doing office works, dual-core (4 logical threads with HT) will be more than sufficient, provided that core frequency is good enough which is, for nowadays, 16+ghz.

Even Alienware M11x with 1.3gbz CPU feels fine for daily tasks.

 

What kind of Core 2 Duo cpu do you have? What is the speed? I suspect in your case you're better off with a Quadcore. I used Excel a lot and the quadcore I had was faster than my current dual core. Excel uses all the cores, so it's easy to understand. Most software do not use more than 2 cores. My 2 cents.

 

Futuremark is a worthless benchmark. Futuremark also shows the 480M beating the heck out of the 5870, when in gameplay situations it's much closer. Look for benchmarks in applications you use.

Word isn't terribly multi-core aware as far as I know, so you'll be slow with that no matter what you do. Best solution for that is a lot of memory, and probably the 620QM as it will have the fastest single-core speed. Again, gotta know what you're really feeling pain with and using it for to get to the right choice The 620M is the absolute fastest single-thread CPU out there, and would be my recommendation if that's one of your common tasks. An i5-540M wouldn't be far behind, and may cost significantly less allowing you to put money into something like an SSD, which is a heck of a performance boost.

 

I don't think what you are experiencing is CPU related. When you use word, the Office creates a hidden shadow copy (temp file) on the same location. When you modify something, it modifies its shadow copy as well.

I think what you need is a SSD.

 

I do not intend to do lots of encoding and rendering, but, despite that, I would like a high-speed processor. I currently have a 2.4 GHz Core 2 Duo and I expect something much faster. Not really looking for a processor which is good enough, but something that can handle most tasks with ease and that will keep running fast for two years. I've got very disappointed with low-end and medium-range processors in the past, and I'm definitely going for a Core i7 this time.

 

You should know that today's CPUs are very adequate, and 2.4 Core 2 Duo is a force to reckon with. The bottleneck of any system is traditional HDD. Once HDD is replaced with SSD, then the bottleneck becomes either RAM or CPU.

 

I couldn't find any benchmarks in real world applications, just these benchmarks which represent theretical situations which won't happen in day-to-day use. And even those benchmarks are not conclusive...

And I'm afraid Endnote is even less multi-core aware than Word - in fact, it seems that its code is quite old, and not very well-engineered.

The i5-520M, i7-620M and i7-720QM are very similar in price in the model I am looking at (no i7-540M available), so the options that make sense are the i7-620M and the i7-720QM. And it seems like these two are very different kinds of processors, one being better for single-threaded and lighthly multi-threaded tasks and the other being faster for heavily-multi-threaded tasks. I don't know how many threads each application uses... is there some software that shows it? (Mac OS shows it, why Windows can't?)

I've considered SSD, but it's too expensive. I can buy a 500 GB 7200 RPM HDs for less than a third of a 80 GB SSD drive...

 

Well, a faster cpu wouldn't be much of use if it cannot feed data fast enough onto disk. That's why I brought up SSD.

 

In fact, I've been monitoring my CPU use and it reaches 80% or higher of usage very frequently. So, I guess a faster CPU would be desired.

SSD is very expensive, but I've seen some benchmarks on the Internet and it's much faster than an HD. Would it make a big difference in speed to have a small SSD drive for installing Windows and the applications and a (large) HD for keeping the data?

 

It should be noted that CPU can have higher load if it has to wait for data to complete writing since CPU has to wait for that task to complete.

 

An SSD drive is very expensive, but I could afford a small one for keeping just the applications, while having an HD to storage data. Would it be much faster than using HD for everything? Or would it be necessary to also have my data storaged on the SSD drive?

 

For your case, applications can be on traditional HDD because your applications (namely Office Word) is not causing bottleneck. It is causing a bottleneck when it is writing data on your HDD.
Therefore, whatever you are working on should be on a SSD or a fast Expresscard SSD so that your application and CPU can write data fast onto the disk as you make modifications.

At least, that is what I believe. I could be wrong here, so I'd wait until some more people add their voices.

 

The price of a large SSD drive for handling all my data would be prohibitive. I can only afford a small SSD drive (not larger than 80 GB) to put Windows and the applications and/or a portion of data. And I will only do that if it considerably speeds up my system, because it is expensive... would it help?

 

SSD right now is an investment and a commitment. Having purchase numerous SSDs so far ranging from 64gb to 128gb, I know it's hard to swallow the price. Though for me, I am not going back to traditional HDD.

That's why I said you should get a second opinion because, to be honest, I am not 100% positive that SSD will solve your issue, but from my understanding, it seems HDD is your bottleneck due to how Office Word works.

If you can find out how to disable Office Word shadow copy, you should be able to decrease your slow down significantly.

 

I thought I asked this question already. Anyway, you specified it more clearly so hopeful the OP will take it to heart this time.

And therein lies the key to answer his question. It's all about the software!

 

Also recommend getting a fast SSD and use a larger HDD for storage.
Install the OS to the SSD and maybe some apps while the rest of the stuff like games or music on the HDD.
And if the notebook only got 1 hdd/ssd slot, you could perhaps replace the optical drive so that you can use a HDD there.

 

Thank you. I think this may be the way to go. I've seen some videos on YouTube and the speed of SSD drives really blows any HD away.

I'm read, though, that SSD drives have a limited lifetime. I've also read somewhere else that technology has improved and that SSD lifetime is not an issue anymore, as drives could last for much longer than someone is expected to use a computer. Does anybody have any clue on this?

 

Yes this is confirmed. The greatest disadvantage that SSDs still have over HDDs is there relatively enormous price difference. Sadly, that will be it's lack of widespread application for some time to come.

 

I've been taking a look at Windows 7 Resource Monitor and it shows how many threads each application use. Here's the thread count for some programs:

Microsoft Word 7: 7 threads
Endnote X3: 5 threads
Firefox 3.6: 24 threads
Google Chrome 5: 31 threads
Internet Explorer 8: 41 threads
VMWare Player 3 (running Windows XP virtual machine): 39 threads
Dropbox: 17 threads
Avast: 46 threads
Calculator: 5 threads

I had no idea these applications used so many threads. No application seems to be single-threaded (even Calculator uses 5 threads). The operating system itself uses hundreds of threads. The whole system should be using about 1,000 threads right now...

 

Thank you. The difference seems to be really astonishing, I've been taken aback by some YouTube videos...

By the way, I've noticed on your signature that you have a quad-core notebook with a Q9000 processor. It's a 2 GHz Core 2 Quad, right? How does it behave with your software? Do you feel it is faster than a 2.8 or a 3.06 GHz Core 2 Duo?

 

My primary reason for choosing the quad-core processor was for video editing purposes since I had intended to install CS4 at the time I bought it. I saw it as an advantage, but to tell you the truth, I haven't put it through any real trials yet since I'm still in the process of learning this editing program.

In addition, I'd need to run it on an equally configured higher speed system to get any definitive results anyway. In theory, the quad core would be superior--despite it's slower clock speed--but that's only because the software is designed to take full advantage of the additional cores. Something most software doesn't do.

Anyway, that's why I chose it over the faster dual core equivalent.

 

You might also want to consider a laptop that can use a real Desktop Quad i7 CPU. I think my next laptop purchase is very likely to be something like that. Also consider whether you want to be able to play GTA IV or not.

 

The main purpose of the laptop is not gaming. But it will have a strong video card anyway (an ATI 5870 or a NVIDIA GTX 280M).

I have found only one laptop with a desktop quad-core i7 (the 900 series). It is a Sager and it would be a great performer, but there are some few drawbacks. It is a very expensive beast (with a nearly prohibitive price), it has a CCFL screen and I have read reviews which say its keyboard is not precise. In fact, it looks like a dinosaur compared to the other Sagers which look much more modern, have a LED screen and seem to have a better keyboard... I definitely don't care about the looks, but a notebook priced so high should have at least a LED display and a good keyboard...

Anyway, from the videos I've seen on YouTube and from what people are telling me in this forum, an SSD drive would be worth more than a desktop Core i7 (instead of a laptop Core i7) for performance, since it would eliminate the HD bottleneck, is that right?

 

Yes, when money no longer becomes an issue, I for one would definitely consider something like that. Along with 16 GBs of DDR3 2333 RAM!

Contrary to popular belief, the SSD does not reinvent the computer.

 

Yes... but I've seen some impressive benchmarks...

 

Benchmarks don't really do justice until you get to use one.

Having said that, you won't notice much differences between a high end SSD and a value line SSD. A value line SSD will take any traditional HDDs, slap it around, steal its lunch money and leave it crying on the sidewalk. ( Linus @ NCIX )

Well, if you move to SSD, the most changes you will notice is vastly reduced boot time and no more waiting as soon as you log in, and that all of your applications will launch as soon as you log in.

 

That is great. And what about actually using the apps? Will they also be faster? May I assume that there are lots of reading/writing on the disk while I am using applications, and that SSD will vastly increase the performance in those cases?

 

almost everyone on a laptop uses their ssd as the os/applications. but in your word example, its the data read/write thats the bottleneck and not the os/application. getting an ssd large enough for fast data performance may be too expensive at this point. you may be better off going for a dual hdd drive raid 0 setup and a fast cpu for your (fast) data requirements.

 

My short answer: If you play (or will play) GTA4, get a quad.

 

in any case , if u are going to get a desktop replacement , get a quad.. after all it is more powerful and also u don't really need battery life..