Why is the i7 720QM "better" than an i5 540M?

[TheGman_GL]

I have the option to buy an i7 720QM or a i5 540M and in every benchmark list I see the i7 outperforms the i5 but I really don't see why. Yes, the i7 is a quad, but it runs only at 1.6GHz and even with turbo mode it only goes up to 2.8GHz, while the i5 is clocked at 2.5GHz and can go up to 3.3GHz. The only noticeable advantage I see is that the i7 has 6MB cache while the i5 is limited to 3MB.

 

[saaiello]

The I7 is a Quad core with hyper threading so it has 4 cores and 8 threads. The I5 is just a Quad core 4 cores 4 threads.

■Hyper-threading works by duplicating certain sections of the processor—those that store the architectural state—but not duplicating the main execution resources. This allows a hyper-threading processor to appear as two "logical" processors to the host operating system, allowing the operating system to schedule two threads or processes simultaneously

 

[TheGman_GL]

I thought the i5 had 2 cores with 4 threads...

Meh, doesn't matter anyways... the thing is that not many aplications use four cores, and why would the i7 be superior if (with one core enabled) it's clocked at 2.8GHz while the i5 would be at 3.3GHz?

 

[saaiello]

I thought the i5 had 2 cores with 4 threads...

I'm sorry you are right I was thinking of the desktop I5 750 for some reason. The I5 540M is dual core with hyper threading 2 cores and 4 threads

 

[TheGman_GL]

In Tom's hardware I found that a Core i3 530 would outperform (in gaming) in some cases an i7 870. I wouldnt be surprised if an i5 540M would be better than an i7 720QM even if the numbers say the contrary...

 

[saaiello]

It really depends on what the uses are and what you are doing. If a program can use all 8 threads the I7 has, then it will be faster on the I7 if you are useing a program that can only use 2 threads then a higher clocked I3 will perform better. So if you are looking for a processor for gaming a higher clocked dual core can sometimes be better but that is only true if the game or program can only utilize 2 threads.

So what I am saying is it will all depend on the program that you are useing.

 

[TheGman_GL]

Yeah, the thing is that the i7 is a quad and the i5 is a pseudo quad (with HT). If both can run aplications that use four cores (a fair head-to-head), wich one is better?

 

[saaiello]

4 real cores is always better.

 

[TheGman_GL]

Even at a lower speed?

 

[saaiello]

Even if the Quad is a few hundred mhz lower 4 cores is better then 2 hyper threaded.

 

[TheGman_GL]

OK... care to explain why?

 

[Dekasav]

Because 4 > 2. Seriously, that's all it really is.

Actually, the reason benchmarks show that the i7 is much faster is because when we benchmark we have a strong tendency to use things that use LOTS of CPU power. These are the same kinds of things that are multithreaded, so in benchmarks, quads come ahead of duals in more programs than in real-world usage (for most people).

Oh, and the i7 is a pseudo oct-core, vs. a pseudo-quad, so it's either 4>2 or 8>4. That, and if it ONLY uses 4 threads, real cores are vastly better than fake ones, simply because a fake one just uses the leftover processing power of a real one.

 

[jimmysmitty]

OK... care to explain why?

The thing with SMT is that a virtual core (basically what it is) only acts as about 70% of a real core. So in essence, if a app or game can use 4 cores, a true quad will win over a fake quad.

 

[TheGman_GL]

Great, so the i7 is really better...

I saw on a test made to the i3 520 that ONLY in encoding and one or two games was beated by an i7 870. In everything else it was on par and even in most cases superior. That's why I asked, because a laptop I was planning to buy comes either with an i5 or an i7, and the i7 is $100 more so I was wondering if it's really that big deal to have a pseudo-oct as Dekasav said.