Using a Quad Core System

Intel's first dual core processors, codenamed Smithfield, were actually the first 90nm Intel CPUs we actually recommended. The reason being that the real world performance improvement brought about by having two cores at your fingertips was simply too much to resist, especially if you were a heavy multitasker. A big reason for the improvement in real world performance came about because of inefficiencies in the way Windows XP's scheduler handled juggling multiple threads, especially on a single core CPU. The move to dual core got rid of many of those nasty Not Responding windows when Windows' scheduler would simply never properly allocate CPU cycles to a particular thread.

Inevitably the same thread juggling problems we saw with single core CPUs would eventually apply to dual core CPUs, just with more active threads. Intel once told us that we'd run into the same sort of scheduler/CPU cycle limitations at a bit over a dozen active threads on a dual core CPU, meaning at that point, it's time for four cores.

We performed a quick test to see if we could spot the real world difference in multitasking and system responsiveness between a dual core and a quad core CPU. We took our test bed and ran as many multithreaded benchmarks as we could feasibly start without completely bogging down the system; we ran our 3dsmax, Cinebench, DivX, WME and iTunes tests all at the same time, not to see how fast they'd run, but to see how responsive the rest of the system would be with a dual core CPU vs. a quad core CPU.

On both systems we had no problems launching Explorer windows or navigating the OS while all of those tasks executed, indicating that we were no where near that saturation point where the entire system becomes unresponsive; good news for dual core owners.

We could switch between all of the running applications without running into a window that wouldn't respond, with the exception of iTunes. Regardless of whether we had two or four cores at our disposal, iTunes would only respond when it felt like it. Although the encoding task was continuing, we couldn't interact with the application without waiting a handful of seconds for it to regain consciousness.

The primary difference between two and four cores in our very heavy multitasking scenario was in the work that got done. While the 3dsmax, DivX, WME and iTunes tests all managed to inch along during our test, with a dual core setup the Cinebench test wouldn't even start until after iTunes had completed. On the quad core setup, Cinebench ran alongside iTunes, albeit at a slow pace.

It's a faint difference but it does highlight an important point - even the heaviest of multitaskers aren't likely to see a huge difference in system responsiveness with four cores vs. two. It is in the performance of individual threads, especially when you have a lot that are contending for CPU time, that you'll see a much bigger difference between Kentsfield and Conroe.

More Cores, but where's the Elegance? More Cores - The Ticket to Power Efficiency?


View All Comments

  • JJWV - Tuesday, January 23, 2007 - link

    I bought a QX6700 for crunching at numbers. The reasoning was simple twice the power, only one MB, disk, PSU, case...

    The result is disappointing, the maximum throughput I get is not twice an E6700, it is just a little more than one an half : 1,6 to be precise. The bottleneck is definitely the memory. The Northbridge cannot communicate fast enough with the memory. 5I came to this conclusion by varying multiplier, FSB...) Perhaps it would be worthwhile with the faster memory available 9200, but I am afraid even that kind of memory is to slow. The Quadcore is where Intel went over the edge with their memory architecture.
  • Kougar - Tuesday, November 14, 2006 - link

    Any ideas on the Apache benchmarks I am seeing with a QX6700? They are appalling at best, with a QX6700 performing on par to a E6400!! A little of the same problem seems to have shown up in Office Productivity benchmarks. Any thoughts on this? Reply
  • in1405 - Monday, November 6, 2006 - link

    <<<No article looking at a new processor release would be complete without benchmarks. However, let us preface the benchmark section by stating that the benchmarks don't tell the whole story. There are numerous benchmarks and tasks that you can run that will actually show quad core processors in a better light. A lot of people will never use the applications related to these benchmarks, so in one sense we could say that most people should already know whether or not they need quad core processing.>>>

    Some interesting comments here on the relevance of Benchmarks .. This looks interesting as this point of view never came up while the AMD CPUs were being glorified a few months back in this same site!! Wonder where the sudden wisdom comes from.
  • LTC8K6 - Sunday, November 5, 2006 - link

    Why not compare dual to quad by trying to run things in the background while you do something in the foreground? Encode something and play Oblivion, for example. Would we finally be able to do anything like that with quad cores? Are we able to get good framerates in such a situation yet?
  • Webgod - Thursday, November 2, 2006 - link

    How about running">DriverHeaven.Net's Photoshop CS2 benchmark? I think one of your standard magazine benchmarks has Photoshop 7, but the DH benchmark is newer and it's somewhat popular. Anybody can download a demo from Adobe, and run the benchmark on their own PC. Reply
  • coldpower27 - Thursday, November 2, 2006 - link

    Check Intel's current price list here:">
  • JarredWalton - Thursday, November 2, 2006 - link

    Actually just the 820 and 914 - 805 didn't get a price cut this month. But I fixed the other two, thanks. :) Reply
  • coldpower27 - Thursday, November 2, 2006 - link

    oh yeah my bad, didn't mean to add the 805 in there.

    by the way, check your email please.
  • OddTSi - Thursday, November 2, 2006 - link

    On page 7 you say "Apple's OS X and its applications have also been well threaded for quite some time..." yet the only two Apple apps in the test (Quicktime and iTunes) didn't scale AT ALL from 2 to 4 cores. I'm not trying to bash Apple here I'm just trying to point out that the facts don't seem to support your assertion. If Apple's media rendering apps - which are some of the easiest to multithread - don't scale well I doubt that the rest of their apps do. Reply
  • mino - Thursday, November 2, 2006 - link

    Maybe cause there is a catch?
    You see, WinXP is not very OSX like, not to mention its apps ;)

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