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    Core 2 Duo, i5 or i7? New Imac : help deciding based on specs


    Hi all,

    I posted something on the Mac forum but I haven't got any replies - however my question is more to do with Core 2 Duo, i5 or i7 Intel chipsets so I'll post here

    Ref: http://forums.devshed.com/mac-help-1...cs-648054.html

    I am looking to purchase the new Imac - the basic spec, 21.5inch 3.06Ghz.

    I'm not that tech savvy when it comes to hardware, but I just noticed the 27 inch version has a the i5/i7 chipset. The models:

    1) 3.06GHz Intel Core 2 Duo processor with 3MB shared L2 cache

    2) 3.33GHz Intel Core 2 Duo processor with 6MB shared L2 cache

    3) (27 inch screen) 2.66GHz quad-core Intel Core i5 processor with 8MB shared L3 cache; Turbo Boost dynamic performance up to 3.2GHz

    4) 2.8GHz quad-core Intel Core i7 processor with 8MB shared L3 cache; Turbo Boost dynamic performance up to 3.46GHz; Hyper-Threading for up to eight virtual cores

    I can see online many technical explanations about the differences between these processors..but could someone tell me, in 'layman' terms, what the difference is? It's obvious that Intel Core i7 will be the fastest..but could someone provide a more detailed (yet layman!) explanation so I can decide which one is the best buy for me?

    I don't want to do any high-end graphics work apart from using Adobe Photoshop for now, just the basic stuff but I do want to get a great spec, a more up to date one, if the price is right.

    Any personal opinions as to which one YOU would get (or not get) and why would be great

    Many thanks!
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    I would atleast go with the i5, core 2 duo just seems so old, and why do they skip core 2 quads?

    really if your not doing alot of high processor tasks you probably wont see much of a difference. The core 2 duo you may end up with some slowish if your multitasking, thats why I say go with the quad.
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    There is a lot of information specified in those lines which would be kind of hard to fully explain without writing a textbook. Additionally, different stats are given for each item so it's kind of hard to compare them exactly on just that information.

    First, you have a clock speed differential. Clock speed gives you the rate which the processor does stuff (but not the rate at which it gets stuff done). You can directly compare the clock speed between the Core 2 Duo processors because they use the same architecture and therefore the amount of stuff they need to do to get something done is the same. The Core i5 and Core i7 processors use very similar architectures to each other, so you can compare those as well. You cannot directly compare the clock speed of the core 2 duo to the clock speed of the core i5/i7 though, because the architectures are different. Basically this means that the core i5/i7 processors don't have to do as much stuff to get something done, so they will be faster even if they are doing stuff at a slower rate. This means that between the same processor architectures higher is better, but you can't compare clock speeds between architectures.

    Next you have the cache difference between the processors. Obviously more is better, but L2 cache is also better than L3 cache. Cache will help with memory speed (but not size) bound programs. It's basically a small amount of memory that the processor uses to duplicate data stored in the main memory. Cache is very very fast compared to main memory. Once again, because you only have L2 cache amounts for the core 2 duo processors and only L3 cache amounts for the core i5/i7 processors you can't directly compare them.

    Next you have the number of cores. This primarily comes into play with multi-tasking, although some applications can take advantage of multiple cores (generally processor intensive applications like video encoders). The more programs you run at one time the bigger of an advantage you will see from having more cores.

    Turboboost is a feature only found in the core i5/i7 processors, basically what it will do is disable 1 to 3 cores and then increase the clock speed in the cores that are still enabled. This means you lose some parallel processing ability (essentially turning the quad core processor into a dual or single core processor) but you gain a significant clock rate increase in the remaining core(s). This is primarily useful when you are running a single application that can not take advantage of multiple cores. Note that this feature kicks in automatically as you're working, it's not something you have to configure manually.

    Hyper-threading means that a single processor core will sometimes do multiple things at the same time. This is possible because a processor core is made of several distinct components that are generally not used at the same time. For example, a single core might have both a floating point arithmetic chip and an integer arithmetic chip but no instructions that use both at the same time. Thus if you have a floating point instruction followed by an integer instruction the processor will process both at the same time. Hyper-threading is generally not a huge benefit because it only helps under very specific circumstances.

    (1) is going to be sufficient for pretty much anything you could want to do. The other options are simply going to run CPU bound things faster.

    I would get the core i7, but not if it forced me to buy a 27 inch display. Honestly, it's kind of B.S. if you have to upgrade from a 21.5 inch display to a 27 inch display just to get a better processor (seeing as the processor has absolutely no bearing on the display). It would probably be cheaper to buy (1) with the 21.5 inch display, purchase a core i7 separately, then pay someone to install it, than it would be to have to pay for the upgrade from 21.5 inches to 27 inches alone (not even including the extra cost for the processor).

    Although you've probably already made up your mind, personally Apple as a company disgusts me, so I would recommend saving yourself a lot of money and getting a PC from a different vendor.

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    Thanks so much for this, very informative. I haven't made my decision yet but I am considering the options, more inclined towards a 21" though as it seems more than enough for me in terms of screen size. I agree about the lack of flexibility in allowing us to upgrade the processor without upgrading the display size.

    I wouldn't mind hearing a few more thoughts on Apple - on why you said that Pls do PM me or message here, as I have been debating to myself about Windows on a PC vs. the Mac.. you generally get a cheaper, better spec on an assembled machine using windows than you do for a Mac which seems a little inflexible. However I always thought that the Mac is way more sturdy and reliable in terms of avoiding repairs and servicing for your machine in say the next 2-3 years from when you buy it. Do you think this is a generally fair assumption?
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    iMac 21" or 27"?


    Originally Posted by rishijd
    Thanks so much for this, very informative. I haven't made my decision yet but I am considering the options, more inclined towards a 21" though as it seems more than enough for me in terms of screen size. I agree about the lack of flexibility in allowing us to upgrade the processor without upgrading the display size.

    I wouldn't mind hearing a few more thoughts on Apple - on why you said that Pls do PM me or message here, as I have been debating to myself about Windows on a PC vs. the Mac.. you generally get a cheaper, better spec on an assembled machine using windows than you do for a Mac which seems a little inflexible. However I always thought that the Mac is way more sturdy and reliable in terms of avoiding repairs and servicing for your machine in say the next 2-3 years from when you buy it. Do you think this is a generally fair assumption?
    Since you've decided to buy one of the new iMacs but haven't made up your mind on which one to buy, I'll paste in a short post I've written on exactly this subject:


    If you're asking yourself this question, you'll find some facts here which will help make up your mind. If cost is not the deciding factor, consider screen size and processing power as your main decision criteria.

    Screen size

    Start with the gargantuan 27-inch iMac screen. You probably have a good idea where the iMac will be placed in your office or home. Measure the space to see if it will physically fit and consider how near or far you'll be seated from the screen. In any case, go to an Apple store or reseller to check it out.

    Remember: the screen is huge. The 2560 by 1440 resolution has so many pixels that you can play high-definition (HD) 1080p movies in native resolution and still have about 77% free space on your desktop. To watch full screen movies, the iMac will need to upscale the HD movies. At 109 pixels/inch density, make sure that your eyes will still be able to see the small type without fatigue (you may want to adjust system preferences to a default larger type).

    The size of the 27" iMac screen is great for people who work with multiple windows opened side-by-side or enjoy viewing movies from a distance. If you really need to hang the screen from a wall (the 27" has a VESA wall mount) or want to use the iMac as external monitor, the 27-inch model is for you.

    Normal mortals resistant to the Siren's Call, will be very happy with the size of the full HD equivalent 1920x1080 screen resolution of the 21.5" iMac. That is still over 2 million pixels of glorious color.

    Processing power

    I'm talking graphics processing unit (GPU) and central processing unit (CPU). The NVIDIA GeForce 9400M graphics processor in the basic 21.5-inch iMac will play HD movies without skipping and runs all iLife apps. If you want to future proof your iMac to greater extent, run pro apps from Apple or play high-frame rate games, I recommend you invest in a dedicated graphics card.

    The higher priced 21.5" model comes with an ATI Radeon HD 4670 graphics processor with 256MB of memory, which is the same GPU installed on the basic 27-inch iMac. Since the GPU in the 27" iMac has more screen to fill, games will run faster on the 21" model. To beat the gaming frame rates on the 21.5-inch iMac, you'll at least have to order the basic 27" model with the optional ATI Radeon HD 4850 graphics card.

    Both 21.5" iMacs and the basic 27" iMac come with a dual core 3,06 GHz Intel Core 2 Duo processing chip. The same chip which was built into the former high-end 24" iMac. For most people, the performance of this chip is more than sufficient for any number crunching tasks you will throw at it in daily life.

    For maximum processing power, only the high-end 27-inch iMac will do. It comes with a 2.66GHz Intel Core i5 quad-core processor, which can be upgraded to an even more powerful Core i7 chip. Once Mac 10.6 Snow Leopard technologies have been included into more apps, you will see a performance boost for these 4-core chips. Presently the real-life performance isn't stellar compared to the 21.5" iMacs.

    Conclusion

    The 21.5" iMac is probably the sensible option for many people, but the lure of having the largest LED-backlit computer screen on the block may be too hard to resist. I first ordered the 27-inch iMac, then cancelled the order and went for the love-it-to-bits 21.5" model. No regrets.
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    Hi, I'm trying to decide which laptop to buy, and your post helped clear a lot of things up for me. I would be even more grateful if you would give me your opinion on

    Dell(TM) Studio 15 Laptop (S541031IN8)
    -Intel® Core™ i5-540M Processor (2.53GHz, 4 Thread, turbo boost up to 3.06GHz, 3M cache)
    -Genuine Windows® 7 Home Premium 64bit (English)
    -3GB 1333MHz DDR3 SDRAM (1 x 2G+1 x 1G) (Work at 1066MHz for Intel Arrandale CPU)
    -320GB 7200RPM SATA Hard Drive
    -15.6 " 720p WLED (1366x768) Display with TrueLife™
    -512MB ATI Mobility Radeon HD 4570

    v/s

    T521138IN9 - Dell(TM) Vostro(TM) 1014 Notebook(OCQT)
    -Intel(R) Core(TM) 2 Duo T6670 (2.2Ghz, 800Mhz, 2ML2 Cache)
    -4GB (2GB x 2) 800MHz DDR2 SDRAM Memory
    -320GB SATA Hard Drive
    -Windows(R) 7 Professional COA Label(INDIA)
    -Mobile Intel(R) Graphics Media Accelerator X4500M HD
    -14.0 inch Wide Display HD (1366 x 768) Anti Glare

    I'm an architecture student, and need to run 3D softwares like AutoCAD, etc. They both cost the same, and to me, the studio seems to be the better option, but my Account Manager at Dell, who's helping me, is suggesting the Vostro, because it's a 'business' model. I'm really confused.

    Will be VERY grateful for any help,
    Bhavika
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    What I don't understand about the new i3-7 processors is why they don't give you the L1 or L2 cache in the technical specifications. If the core duo has 4mb of L2 it's probably going to be faster than an i3 with little/no L2 cache, right? I've heard the i/x don't need L2 cache because there is a straight path to access memory but is this true? It's hard to find any good information that verifies this--pretty much just people on forums saying it's the case.
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    I've heard the i/x don't need L2 cache because there is a straight path to access memory but is this true?
    No it's not true. Physically speaking, L1, L2 and L3 caches are able to retrieve data much much faster than main memory. It doesn't matter how direct the path between the CPU and the main memory is because there is such a massive difference in speed between the cache and the main memory. Comparing an on-chip cache to main memory is like comparing main memory to swap space on a magnetic disk.

    Additionally, it's not possible to have an L3 cache without having both an L1 and an L2 cache. If you only had one cache it would be called an L1 cache, if you only had two caches they would be L1 and L2. In order to have an L3 cache, you must first have L2 and L1 caches.

    All desktop based i7 processors have four 256 KB L2 caches (one dedicated to each core) and one 8 MB L3 cache (shared between all four cores). Actually, I believe that all i3, i5 and i7 processors have one 256 KB L2 cache per core and a shared L3 cache of varying size. I don't know for sure, but I also believe that all of them have one 64 KB L1 cache per core as well (32K for data, 32K for instructions).

    Marketing reasons aside, my guess is that the L1 and L2 sizes for i3/i5/i7 processors are not published in most technical specs because they are the same for all models of the processors and therefore meaningless when it comes to comparing them.

    If the core duo has 4mb of L2 it's probably going to be faster than an i3 with little/no L2 cache, right?
    No. You can't assume that the L3 cache in an i7 is slower than the L2 cache in a core 2 duo. The L2/L3 designation signify the level of the memory hierarchy that the cache is at, but doesn't tell you anything about how fast it is other than the fact that an L2 in one CPU is going to be faster than the L3 in the same CPU.
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    Originally Posted by E-Oreo
    Additionally, it's not possible to have an L3 cache without having both an L1 and an L2 cache. If you only had one cache it would be called an L1 cache, if you only had two caches they would be L1 and L2. In order to have an L3 cache, you must first have L2 and L1 caches.
    That was my understanding, too, but why then do most spec sheets give L3 (sometimes L2) and never L1? Is it just because the L1 and L2 are lower and it's a marketing scheme? I'm most concerned about the cache on the actual processor (L1/L2) so when I don't get that information it doesn't make me want to buy the processor but the exact opposite.
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    Actually I don't think marketing has too much to do with it.

    L1 is not normally specified because (a) almost without exception, all processors of a particular micro-architecture have the same size L1 cache and (b) comparing L1 cache sizes between micro-architectures is meaningless. This makes the L1 specification worthless when comparing two processors.

    There are no mainstream desktop processors on the market today that don't have an L1 cache, and in the vast majority of cases it's either going to be 64kb (intel core 2 / iX) or 128kb (amd k10) dedicated to each core.

    L2 cache is often specified for dual core processors which usually don't have an L3 cache. In these cases, the L2 cache is shared between both cores of the processor and tends to vary from model to model.

    L2 cache is often not specified for quad core processors which usually do have an L3 cache. Most quad core processors have independent L2 caches for each core and an L3 cache that is shared between all cores. In cases where L2 cache size is not specified it is usually for exactly the same reason as when L1 is not specified (ie: all processors of that micro-architecture have exactly the same L2 cache size).

    L1, L2 and L3 caches are all located directly on the processor die.
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    Dell Studio 15 or Vostro?


    Bhavika,

    Studio 15 is definitely better, the issue is between Core 2 Duo or Core i3 or Core i5. I have a Studio 15 Core 2 Duo and am very satisfied.

    Sanjiv (9930064075)

    Originally Posted by bhavika1990
    Hi, I'm trying to decide which laptop to buy, and your post helped clear a lot of things up for me. I would be even more grateful if you would give me your opinion on

    Dell(TM) Studio 15 Laptop (S541031IN8)
    -Intel® Core™ i5-540M Processor (2.53GHz, 4 Thread, turbo boost up to 3.06GHz, 3M cache)
    -Genuine Windows® 7 Home Premium 64bit (English)
    -3GB 1333MHz DDR3 SDRAM (1 x 2G+1 x 1G) (Work at 1066MHz for Intel Arrandale CPU)
    -320GB 7200RPM SATA Hard Drive
    -15.6 " 720p WLED (1366x768) Display with TrueLife™
    -512MB ATI Mobility Radeon HD 4570

    v/s

    T521138IN9 - Dell(TM) Vostro(TM) 1014 Notebook(OCQT)
    -Intel(R) Core(TM) 2 Duo T6670 (2.2Ghz, 800Mhz, 2ML2 Cache)
    -4GB (2GB x 2) 800MHz DDR2 SDRAM Memory
    -320GB SATA Hard Drive
    -Windows(R) 7 Professional COA Label(INDIA)
    -Mobile Intel(R) Graphics Media Accelerator X4500M HD
    -14.0 inch Wide Display HD (1366 x 768) Anti Glare

    I'm an architecture student, and need to run 3D softwares like AutoCAD, etc. They both cost the same, and to me, the studio seems to be the better option, but my Account Manager at Dell, who's helping me, is suggesting the Vostro, because it's a 'business' model. I'm really confused.

    Will be VERY grateful for any help,
    Bhavika
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    Did you get a reply?


    Hi Bhavika,
    So did you finally get an answer for your question. Which laptop did you buy and what was reason for the decsion. I am also stuck with same question. Thanks. kiran


    Originally Posted by bhavika1990
    Hi, I'm trying to decide which laptop to buy, and your post helped clear a lot of things up for me. I would be even more grateful if you would give me your opinion on

    Dell(TM) Studio 15 Laptop (S541031IN8)
    -Intel® Core™ i5-540M Processor (2.53GHz, 4 Thread, turbo boost up to 3.06GHz, 3M cache)
    -Genuine Windows® 7 Home Premium 64bit (English)
    -3GB 1333MHz DDR3 SDRAM (1 x 2G+1 x 1G) (Work at 1066MHz for Intel Arrandale CPU)
    -320GB 7200RPM SATA Hard Drive
    -15.6 " 720p WLED (1366x768) Display with TrueLife™
    -512MB ATI Mobility Radeon HD 4570

    v/s

    T521138IN9 - Dell(TM) Vostro(TM) 1014 Notebook(OCQT)
    -Intel(R) Core(TM) 2 Duo T6670 (2.2Ghz, 800Mhz, 2ML2 Cache)
    -4GB (2GB x 2) 800MHz DDR2 SDRAM Memory
    -320GB SATA Hard Drive
    -Windows(R) 7 Professional COA Label(INDIA)
    -Mobile Intel(R) Graphics Media Accelerator X4500M HD
    -14.0 inch Wide Display HD (1366 x 768) Anti Glare

    I'm an architecture student, and need to run 3D softwares like AutoCAD, etc. They both cost the same, and to me, the studio seems to be the better option, but my Account Manager at Dell, who's helping me, is suggesting the Vostro, because it's a 'business' model. I'm really confused.

    Will be VERY grateful for any help,
    Bhavika
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    hi i'm confused too the original response to this thread said go with i5 cos core 2 duo is outdated:

    but the latest alienware m11x from dell has a core 2 duo processor and that's apparently great although it's only 1.3 mhz.

    is i5 2.4 ghz really better? cos dell are selling it a lot cheaper than the core 2 duo in the m11x...........?
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    Core i5s are more expensive than Core 2 Duos in general, but amy not be in every case if the clock speeds are very different. I would check what other options are different on that computer to see why there is a price difference.

    As for the Vostro vs. Studio, in this case I'd go with the Studio. The Vostro does have a 1 gig more RAM, but the Studio's RAM is DDR3 while the Vostro's is only DDR2. DDR3 will mean your computer can access the RAM at a much higher speed. That coupled with the new Core i5 processor should give you much better performance from the Studio.
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    yup, studio is better to some extent

    Comments on this post

    • jzd disagrees : 1. This is an old post 2. Your not really saying anything
    • Arty Ziff agrees : Balance

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