i5/Dual core vs i7/Quad core?

Hey guys!

I'm, well, completely new to computer specs here and was hoping to learn some more about it. In this case, I was hoping to find out more about processors.

In the case of the dual core vs quad core, I was wondering whether one would prefer a high end dual core or a lower end quad core if both were within the price range needed.

For example (and it's truly an example, I searched for the fastest two I could find to compare), which of these two processors would one rather get?
i5-2520M, 2.5-3.2GHz, (32nm, 3MB L3 cache)
i7-2670QM, 2.2-3.1GHz, (32nm, 6MB L3 cache)

I've read people saying that getting a quad core is better for future proofing, but does that still apply when the i5s clock higher than the i7s? Also, how much does the cache matter? (These are probably blatantly obvious to many and I apologize for my complete incompetence, but you've got start somewhere eh?)

Thanks.

 

It varies really to how you use your laptop. If you are power user that runs lots of applications and requires pure raw power, the i7 Quad is by miles better and longer lasting than the i5 Dual. Even if the i5 has a higher clock speed than the i7, the i7 can use more cores to get an application task completed than the i5.

Therefore, when comparing clock speeds like that, I still think that the i7 has more power than the i5 due to more Cache and Cores and that being slightly weaker on the clock speed doesn't hinder it enough to be any worse than the i5 in single/dual core performance.

With that said, if you are using your laptop for just basic tasks like Office, YouTubing or watching Videos etc. or you want more battery life, then the i5 is better than the i7.

It is really just down to how you use your laptop in the long run. For me, I prefer a Quad i7 over a Dual i5 for overall better long-term performance, but you will suffer from battery life a bit though.

 

Star Forge pretty much nailed it.
The cache easily negates the measly 100mhz clock difference, before you add in the extra cores.

One thing though, if the I5 had an SSD, I would take it over the I7 given equal specs otherwise. An I5 is plenty fast, the SSD just puts it way ahead of the I7. If you have no inclination of changing it yourself, that would be the better option.

Quad is better for future proofing, but an I5 will be viable for quite a while yet. It's a heck of a processor. I7 is just the cherry on top

 

extra cache rarely benefits the user in most consumer applications. its usually benchmarking and HPC applications that see an increase in performance. Of course, there are exceptions to every rule, but if you need the extra cache, you'll know it.

that said, go with the i7. its good because you don't lose too much clock speed and get two extra cores; not because of the extra cache.

EDIT: just a general tip, with i-series, the laptop CHASSIS has to do with alot of performance. if you don't have enough cooling, you won't be able to hit your max turbos/hit them for very long.

 

I've read that new CPUs don't use all their cores unless they detect that all the cores/threads are necessary- does this mean that a quad core would use as much power as a dual core if only two of the four cores are working? Would this ever actually happen?

Also, in the case of programs that can only use up to two cores: would the i7 show diminished capability, or would it still perform close to, if not completely, on par with the i5?

Side note: Does Turboboost activate automatically, and is there a way to manually do it should it fail to do so automatically?

Does an i5 work better with an SSD than an i7, or are you just saying that were an i5 and SSD to cost the same as the i7 upgrade, the i5 and SSD combo would be a better choice?

Also, for games such as Starcraft 2, would a decent GPU (i.e. GTX 560) still be the bottleneck, or would it be up to the CPU?

Thanks!

 

Turboboost works automatically. For instance my 2720QM says it is base clock at 2.2 GHZ in reality will usually run at 3.0 GHZ on High Performance power settings in W7. Also, the cores in a Quad i7 will not shut down if they aren't being used but because W7 will always use the physical cores a CPU has to its advantage when it can. What will the CPU do when it needs to only run a two-thread application is Turboboost the two active cores running for that application to a higher multiplier, so for my 2720QM it will hit 3.2 GHZ in a two-thread setup.

With that said it is because the actual cores don't turn off when they aren't really needed is the reason why i7 Quads will always drain more power than a i5 Dual but the small 200-300 MHZ loss in Turboboosted and normal base clock frequencies vs. the rates of a i5 Dual are considered moot and negligible in the Sandy Bridge architecture. The current era of CPU's are not like the CPU's of the past where the "Gigahertz Wars" was the benchmark of speed. A higher frequency these days doesn't always mean it is better and even small MHZ boosts from one CPU to another on the same architecture doesn't give a significant gusto in boost than what CPU's back then used to be.

In other words, yes the 2670QM will be just as good or better than the 2520M when tasked with two-threaded or two-core applications. It is only down to battery life if you want to pick between the two. If battery life is important to you, then the i7 Quad is better for the long run.

Also, Starcraft 2 is a very CPU-dependent game. It will run better with a quad core than a dual core since it will take advantage of up to three cores on any capable CPU. With that said, it also uses quite a bit of GPU gruntwork as well. Furthermore, SSD performance are independent of CPU's. SSD's will work just as well on a quad core as it will on a dual core.

 

One more thing to add is that if you have a dual or triple threaded app, that still leave a full core for all the background stuff should you need it. As for SCII, there are some scenarios where the CPU will definitely be the bottleneck.

 

that is exceptionally difficult to say. in theory, yes, pretty much everything you wrote would be [mostly] accurate. in practice, it really depends on the mood of the OS that day.

for instance, if both threads are 'light' workloads, then it might be scheduled on one core. if they are two threads from a video encoder however, they would most definitely be spread across two cores. unless the OS and application decide that they would benefit from sharing L2 cache, then they would both be scheduled on the same core....its really hard to say. I'm not even going to go into how often a threads are bounced between cores(in windows at least).

EDIT: don't sweat things like this. the chances of you maxing out either CPU without running benchmarks/video encoders is nil to none.

 

One thing though, if the I5 had an SSD, I would take it over the I7 given equal specs otherwise. An I5 is plenty fast, the SSD just puts it way ahead of the I7. If you have no inclination of changing it yourself, that would be the better option.

 

The SSD only affects load times. It won't help against anything involving CPU calculations and rendering. An i5 + SSD for coding or video rendering will still be crushed by a i7 + Traditional HDD. Now the best combination is the i7 + SSD if you can afford it.

 

Most things don't completely load a cpu for a long time, so the processor waits on the drive. Open task manager and watch as you use your computer and see how often your cpu maxes out. Why is it not maxing out? It needs data. Hard drives have been the bottleneck for years.


SSD's only effecting load times was born from flawed logic.
I have SSD's in my desktop and laptop, and there is no way I'm going back.

The best spinning drives don't fully load sata2, but the best do use most of it, an ssd can go well beyond that, but if you only have sata2, you will barely see any difference. On startup, Windows loads lots of small files, which means access times trumped bandwidth. Large files need bandwidth more than access times. This was the problem on my last system and early SSD's (which barely flowed more than sata2), everything was faster, but only a little. A switch to sata3 and my drive now pushes twice what a normal drive can, and yes, it very much makes a difference.

Examples from my desktop... (yes, I know, it's not a laptop, but still)
Restart - 40 seconds, half of that is bios.
Adobe Photoshop CS4 64bit - 3 second load time (first run), used only 10% cpu
Firefox 64bit beta - 1 second load time (first run)
Left4dead2 - I get stuck waiting for the servers to sync instead of waiting for maps to load.


Edit: Had a friend load Photoshop CS4 64bit on her recent HP desktop, load time was 11 seconds.

 

So for CPU (or even GPU, though I doubt its relevance) intensive programs, such as games (the example of Starcraft 2 once more comes to mind), would one rather upgrade from a dual core to a quad core, or would an SSD offer the most significant performance boost?

And just a side question regarding SSDs: I've heard but cannot confirm that HDDs slow down as they fill up. Assuming this is true, is it the same with SSDs? Also, what brand of SSDs is usually best (in terms of reliability, speed, and price?) Doesn't need to be one brand with all, but I'm just curious in who wins in each category.

Once more, many thanks.

 

As stated before, SSD's only help load times and caching. Meaning if you want to load up a program or booting, SSD's are fast, fast, fast. They DON'T help in anyway whatsoever in improving rendering or crunching data. Therefore a SSD will help loading times when you start a SC 2 match, but it won't help at all during the game. The CPU and GPU will take the grunt work for rendering all the graphics, code, scripting when you play.

Therefore for gaming, the CPU is a better choice. However most people who wants to shed loading times of applications and Windows booting will say overall the SSD give you the most noticeable improvement in daily computing usage.

 

I doubt Starcraft can take advantage of 4 cores. Few games do. That being said, 4 core is more future proof.

All drives slow as they fill up due to fragmentation. As you fill it leaves fewer and fewer large spots for files to sit as a whole, so they are broken into pieces. As the system reads that file, it has to ask where each piece is before it can access it, the more fragments, the more times it asks and the slower it gets. This problem isn't as much of an issue on SSD as long as they support TRIM, which keeps things tidy.

It's going to depend on the exact type of compression being done.

While the CPU is more important, most everything written on SSD for compression was written 2 years ago when SSD's were still new. Processors and SSD's have doubled in speed and power since then. Spinning drives on the other hand, have stagnated for the last 3 years or more and have only focused on capacity.


The CPU is almost irrelevant in games these days so long as you have enough memory and a decent video card and therefore of no more use than the SSD.


Edit: All that being said, I don't think laptops should be used for hardcore rendering or video compression, most simply can't handle it long term.

 

While SCII doesn't use 4 cores, having one or two extra cores for the rest of the background tasks helps. I went through an article a while back, and SCII performed better on 3 cores than two at the same clock speed. Of course, considering the i5 is clocked slightly higher, i'm not certain which way the scales would tip. I'd venture in favor of the i7, but that is a guesstimate as i have no real world data to back it up.

HDDs will slow down as they get near full capacity due to both fragmentation and also the fact that the drive will have to operate closer to the inside of the platters where the read/writes are a little bit slower. This doesn't matter much if you aren't using the drive as an OS drive.

Regarding HDDs, they have gotten slightly faster as platter density has increased. There is not that much of an increase, but pitch a WD Scorpio black 750GB against a 7200RPM drive of two or three years ago with smaller capacity and you'll see a small difference in things like boot times. Nothing as spectacular as a SSD, but still a difference.

As for the CPU being irrelevant in games, again that depends which game you play. For most games it is true that doesn't really matter, but there are always exceptions and if games you play are one of those, then go for the i7.

 

as a general rule, RTS games use CPU more, while FPS games use the GPU more. once again folks...thats a general rule, don't throw a hissy fit if it doesn't apply to your specific game.

 

I've always craved to ask this question- how do hybrid HDDs work?

Also, when the clock speeds between the i5 and the i7 increase (with the i5 becoming greater and greater than the i7, though quite uncommon) such as with the following, is there a point where the i5 becomes more effective? Or are the extra 2 cores and cache still greater than the clock rate difference in terms of significance?

Example:
2nd Generation Intel® Core™ i5-2430M, 2.4-3.0GHz, (32nm, 3MB L3 cache)
2nd Generation Intel® Core™ i7-2630QM, 2.0-2.8GHz, (32nm, 6MB L3 cache)

 

For video encoding - all core i5 and i7 SNB CPU's have Quick Sync. MUCH quicker and just as good as software encoding if it's set to quality.

I say an i5 with an SSD. You won't see too much difference in Photoshop with an i7, unless you're on a super-huge workload. The i5 with an SSD will blow you away.

Plus if battery means anything, go i5. The i5, from my experience, is much more efficient than the i7 at mundane everyday tasks like web-browsing and such. When you get into heavier workloads, the i5 still has 4 threads and turbo-boost. IMO, the i5 is a GREAT choice because unless you intend on really utilizing an i7 to it's peak, it's not worth it's price.

 

In basic terms, hybrid HDDs have a few GBs of fast flash memory where frequently-accessed information can be cached, providing SSD-like access to some data, speeding up some usage patterns. The difference provided by this flash memory is greater in some tasks than others.

If a program is multi-threaded for quad cores, a lower-clocked quad core will likely outperform a higher-clocked dual core. If the program is single-threaded, on the other hand, a higher-clocked dual core will have the advantage.

As for which one to choose, I personally would say that the price difference and battery life needs are the primary factors that should dictate your choice. If neither matters, then a quad core would be a smarter choice.

 

This information will remain unchanged with Ivy Bridge, correct?

 

Short answer: yes.

More accurate long answer: As quad core CPUs become more power efficient with Ivy Bridge, they may become more practical for people who need 6+ hours of battery as well and laptops that aren't 15+ inches. But ultimately, the difference between dual and quad core CPUs will remain, because dual cores will also become more power efficient.

 

Like what MidnightSun and I have been trying to say that it is all up to how you want to use your laptop in the long run. Dual cores are still powerful and efficient if you are always going to be on battery life and on the go. If you want to use your laptop like a true mobile workstation, then the dual core is sufficient and the way to go. However if you need power and will be finding yourself almost plugged in doing lots of resource-intensive work and only carrying the laptop from like your office to your home via car, then the quad core would be the more preferred choice and such.

You can't go wrong with any Intel dual or quad core CPU. It is all down to what you want from your laptop and how you use it. The pros and cons you weigh out will ultimately make you decide which kind of CPU will suit you the best for the next few years.

 

on the issue of battery life, people vastly overestimate the benefits of newer cpus in extending runtime. the reason for this is the power reduction is relatively small between generations and also because the CPU isn't a major consumer of power relative to the screen.

 

What is used most for screen capturing (i.e. Fraps, etc)? I realize that it's the GPU that's mainly responsible for framerate in most programs (especially games), but is it the CPU or hard drive that's most responsible for the smoothness of screen capturing and framerate while recording?
Thanks

 

Mainly the hard drive. Fraps does very little compression on the footage it records, so naturally the data rates are pretty high. It's a compromise really, you could leave it completely uncompressed and end up needing a high end SSD to record because the data rates are pushing 500mbs, or you could try to compress it a lot and lose a lot of performance in the process.