The CPU Question: Slow Quad-Core or Fast Dual-Core?

Normally when you compare two similarly priced PCs these days the specs are extremely close. For whatever reason, with all-in-ones, the specs couldn't possibly be more varied. Dell ships all of its XPS One 24s with an Intel Core 2 Quad Q8200 (2.33GHz) while Apple offers either a 2.80GHz or 3.06GHz Core 2 Duo in its 24" iMacs, leaving us with the not nearly age-old discussion of what's better: a fast dual core or a slow quad core?

In the early days the decision was simple, you only gave up a small amount of clock speed if you opted for quad-core over dual (around 266MHz) but in today's comparison the difference is a bit more staggering. The top end iMac gives you a processor that runs its two cores 733MHz faster than the four cores in the Dell, not to mention that those two cores have more cache than is split among four cores in the XPS One 24. Apple's got a higher clock and more cache, but Dell has more cores, so which is better?

Back when AMD introduced its triple-core Phenom parts I put together a little table illustrating the speedup you get from one, two and four cores in SYSMark 2007:

  SYSMark 2007 Overall E-Learning Video Creation Productivity 3D
Intel Celeron 420 (1 core, 512KB, 1.6GHz) 55 52 55 54 58
Intel Celeron E1200 (2 cores, 512KB, 1.6GHz) 76 68 91 70 78
% Increase from 1 to 2 cores 38% 31% 65% 30% 34%
Intel Core 2 Duo E6750 (2 cores, 4MB, 2.66GHz) 138 147 141 120 145
Intel Core 2 Quad Q6700 (4 cores, 8MB, 2.66GHz) 150 145 177 121 163
% Increase from 2 to 4 cores 8.7% 0% 26% 1% 12%

 

The purpose of the table was to show that while the move from one to two cores is justifiable for the vast majority of users, going from two to four isn't nearly as high yielding. The issue is that while most applications these days are multi-threaded, they are either still bound by the performance of a single thread or they are only able to split the workload two ways, meaning half of the cores on a quad-core CPU would be left with nothing to do. The exceptions are things like video encoding or 3D rendering as you can see from the results above.

To get an idea of general system performance between these two machines I turned to PCMark Vantage, which actually does a good job of comparing similar CPU architectures in a handful of general purpose tests. I'm going to highlight the important tests that really show where these two systems perform the most differently:

PCMark Memories 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
CPU Image Manipulation 3.78 MB/s 3.319 MB/s
HDD Importing pictures to Windows Photo Gallery 26.533 MB/s 31.38 MB/s

 

The PCMark Memories 1 test is actually a multitasking test with two things happening at once; some basic image manipulation is being performed alongside importing pictures into the Windows Photo Gallery. Both of these tasks are multithreaded and thus there's an actual advantage to having more than two cores, which is why despite the clock speed deficit Dell's XPS One 24 is able to pull ahead.

PCMark Memories 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Video Transcoding VC-1 to WMV9 2.681 MB/s 3.075 MB/s

 

The Memories 2 test is a simple video transcoding test going from VC-1 to WMV9, and here we see the quad-core advantage once more. The TV and Movies 1 suite also performs a video transcoding operation but this time while playing back a HD-DVD, while both systems are able to play the video back at full frame rate the transcoding task completes faster on the quad-core Dell system.

PCMark TV and Movies 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Video Transcoding (VC1 to VC1) 0.435 MB/s 0.664 MB/s
Video Playback VC1 HD-DVD with SD commentary 29.46 fps 29.44 fps

 

The TV and Movies 2 test is similar to the one I just mentioned, here we're playing a slightly more stressful HD-DVD source but hitting the disk in an access pattern similar to what would be used in Windows Media Center. Once again both systems pull off the video playback just fine, but the Dell machine is twice as fast when it comes to the disk portion of the test thanks to its extra cores.

PCMark TV and Movies 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
HDD Windows Media Center 25.007 MB/s 44.642 MB/s
Video Playback VC1 HD-DVD with SD commentary 29.431 fps 29.432 fps

 

The Gaming suites clearly go to the iMac; most games don't use more than two threads and Apple's dual cores are clocked much higher than Dell's four, not to mention that the iMac has a much faster GPU as well. If you want to game, the iMac is the way to go (that still feels weird to type).

PCMark Gaming 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Data Decompression 764.975 MB/s 796.299 MB/s
GPU Gaming 22.4 fps 9.8 fps

 

PCMark Gaming 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
CPU Gaming 8726.193 ops/s 7518.558 ops/s
HDD 10.692 MB/s 11.054 MB/s

 

The Music 1 test is a light multitasking test, here we're viewing web pages, transcoding a MP3 to WMA format and adding music to a Windows Media Player library. The web task is faster on the iMac, while the other two tasks are slightly faster on the Dell. I'd call this one a wash, the two perform about the same.

PCMark Music 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Web Page Rendering - Music Shop 14 pages/s 12.167 pages/s
Audio Transcoding (MP3 to WMA) 0.578 MB/s 0.633 MB/s
HDD Adding Music to WMP 4.953 MB/s 5.06 MB/s

 

The second test is simply transcoding a WAV file to WMA lossless, basically backing up a CD. I haven't seen audio transcoding optimized for more than two threads, so it makes sense that Apple takes the advantage here - the iMac is around 27% faster than the Dell XPS One 24.

PCMark Music 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Audio Transcoding WAV to WMA Lossless 8.884 MB/s 6.971 MB/s

 

The PCMark Communications 1 suite runs three tasks, here we're encrypted data, compressing data and running rules on a Windows Mail inbox. Despite the multitasking nature of the workload, it's simply not heavily threaded enough to stress all four of Dell's cores, Apple takes the clear win here.

PCMark Communications 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Data Encryption (CNG AES CBC) 4.211 MB/s 3.655 MB/s
Data Compression 4.797 MB/s 3.085 MB/s
Windows Mail - Copying 9.807 ops/s 4.605 ops/s

 

The same goes for the 2nd communications suite, it's a 3 task scenario but the iMac pulls ahead in each of the three tasks.

PCMark Communications 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Web Page Rendering - News Serial 2.229 pages/s 1.776 pages/s
Data Decryption (CNG AES CBC) 112.91 MB/s 92.977 MB/s
HDD Windows Defender 11.183 MB/s 10.665 MB/s

 

The last two Productivity suites echo what we've seen thus far, take out video encoding/decoding and the quad-core choice just doesn't make sense; a faster dual core wins.

PCMark Productivity 1 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Text Editing 861.106 KB/s 597.045 KB/s

 

PCMark Productivity 2 Apple iMac 24" (Core 2 Duo 3.06GHz) Dell XPS One 24 (Core 2 Quad 2.33GHz)
Windows Contacts - Searching 17865 contacts/s 12778 contacts/s
Windows Mail Searching 8.444 ops/s 4.901 ops/s
Web Page Rendering - Favorites Group - Parallel 1.424 pages/s 1.508 pages/s
HDD Application Loading 2.61 MB/s 2.551 MB/s

 

What's interesting here is that there is no clear victory, while I'd venture a guess that the vast majority of users would benefit from the 3.06GHz Core 2 Duo in the iMac, it really depends on your usage model. If you are doing a lot of video editing, video encoding/transcoding and image manipulation - basically if you're using this thing as more of a workstation, then you're better off with the Core 2 Quad Q8200 in the Dell. If you're doing lighter multitasking, general usage stuff or basically anything other than 3D rendering/video manipulation, you'll find the iMac faster - even under Windows. Strange.

Input Device Wars Can You Game on It?
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  • Eidorian - Thursday, October 30, 2008 - link

    It's not that hard.

    8800M GTS > 9600M GT
  • HanSolo71 - Thursday, October 30, 2008 - link

    thanks for the top gear reference i wish more people in america would actually get that
  • sxr7171 - Tuesday, November 4, 2008 - link

    Well we have BBC America. But people don't watch it much.
  • Jovec - Thursday, October 30, 2008 - link

    Well, that is the behavior of the MS Intellitype software - it will only control iTunes if it is in the foreground. By contrast, Logitech's Setpoint will control iTunes in the background. I have no idea if Logitech does something extra to make this work, or if MS is purposely limiting their keyboards. Had this exact same issue that encouraged me to move back to a Logitech KB.
  • mfed3 - Thursday, October 30, 2008 - link

    this has to do with the keypresses binding to windows commands. they will all work in media player, media center, and all windows programs.

    it has to do with itunes controls not mapping directly to the same commands.

    logitech's software must look at the media process running and send the correct command
  • epyon96 - Thursday, October 30, 2008 - link

    Not sure why the author insists on having a Mac OSX bias. I see nothing wrong with the Start menu nor do I find it outdated. Usually, it's 3 clicks max to get to a program with minimal mouse movement. I am not saying Mac OSX has a bad interface but I see nothing wrong with the Start menu unless you are a devoted OSX fan.

    I am slightly annoyed why Apple still insists on a single button mouse. For some strange reason, Jobs still insists that computer users are too stupid to learn to effectively use a two button mouse. So what does he give us? A one button mouse that tries to emulate two-button mouse behaviour. Sure it looks cool and has that novelty effect but it wears off after the showroom. It begs the question why?

    What does the article mean when it says that the 24" inch flat panel monitors have trouble with 24 FPS 1080 Non-interlaced Blu ray playback? Is it trying to say that 24 FPS refresh rate is not possible on the flat panel without ghosting?

  • CMcK - Friday, October 31, 2008 - link

    Apple haven't shipped a single button mouse with desktops or laptops for a few years now. The Mighty Mouse has four buttons - left, right, side (squeeze) and centre (press the trackball). Very useful. I have mine set for left click, right click, Expose and show desktop.

    Even the single, or indeed no button, Apple laptops have a left and right click. Just place a second finger on the trackpad and press the button or pad and you have a right click.

    I don't find that I actually need to right click often while using OS X.
  • mikeepu - Friday, October 31, 2008 - link

    Frankly I don't really sense a bias in the article. If anything the author is critical of both systems and just states his (keyword alert) 'personal' preference at the end of the article.
    But I do agree with you that there is nothing wrong with the Start Menu, its just that the Apple Dock is simpler in that only one click is required to start a program located on the dock or just two clicks if you have the Applications folder (the equivalent of the Programs folder in the Windows Start menu) attached to the Dock. But then again, where’s the harm in a few extra clicks to get to a program?

    But man Do i want that Dell all-in-one for a Desktop media center :)
  • MrDiSante - Thursday, October 30, 2008 - link

    I am also surprised at the obvious pro-Mac OS X bias in the article. Usually Anand is far more impartial, but this is more than a bit on the Engadget side. Pretty as Mac OS X is, I find that Vista actually offers the more practical solutions to task management problems.

    The taskbar is far better at showing the user what is and isn't running than the dock (something that Microsoft is mistakenly changing with Windows 7 and will hopefully reconsider). As the fact that there is text with the icons allows me to efficiently differentiate between the numerous windows I have open (again, something Microsoft should not change; OS X looks prettier, but Vista takes the usability prize here).

    The start menu still makes more sense than Apple's solution since there is in fact a central place to go for all of your programs (although I personally think Linux does a better job of that).

    Alt+tab scales far better than expose does. They both work fine if you're running 5 or fewer programs, but expose just gets messy really fast if you exceed that. If you have 10 or more programs open, with stickies gadgets/widgets etc, then Expose gets downright unusable.

    Finally, Windows tends to be far more shortcut friendly. Start + number, and start + 3-4 characters + enter usually launch just about any application I need. Alt+tab switches to just about any program I need. Expose and the dock both struggle with shortcut-friendliness.
  • DCstewieG - Sunday, November 2, 2008 - link

    Actually Apple was first on the shortcuts you're talking about. Pressing Apple+Space brings up Spotlight which lets you type the first few characters of the app to find it and Enter to run it.

    As for Anand's Mac bias, it's a very interesting story. Here you have a devoted editor of a PC hardware site who decided to give a Mac a spin for a month to write an article about it. What happens? He becomes a huge fan in the process.

    You see a lot of comments saying that people use Macs because Steve Jobs put them in a trance or because they look nice or something, but here's a guy who came in fresh and decided he liked it a lot by actually using it.

    If you haven't read it: http://www.anandtech.com/mac/showdoc.aspx?i=2232">http://www.anandtech.com/mac/showdoc.aspx?i=2232 (though it is a bit outdated now)

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