Memory Performance - Not Very Nehalem

Let’s start at the obvious place, memory performance. Nehalem moved the memory controller on-die, but Clarkdale pushes it off again and over to an on-package 45nm graphics core.

To make matters worse, the on-package chipset is a derivative of the P45 lineage. It’s optimized for FSB architectures, not the QPI that connects the chipset to Clarkdale. Let’s look at the numbers first:

Processor L1 Latency L2 Latency L3 Latency
Intel Core i7-975 4 clocks 10 clocks 34 clocks
Intel Core i5-750 4 clocks 10 clocks 34 clocks
Intel Core i5-661 4 clocks 10 clocks 39 clocks
AMD Phenom II X4 965 3 clocks 15 clocks 57 clocks
Intel Core 2 Duo E8600 3 clocks 15 clocks  

 

L1 and L2 cache latency is unchanged. Nehalem uses a 4-cycle L1 and a 10-cycle L2, and that’s exactly what we get with Clarkdale. L3 cache is a bit slower than the Core i7 975, which makes sense because the Core i5 661 has a lower un-core clock (2.40GHz vs. 2.66GHz for the high end Core i7s) Intel says that all Clarkdale Core i5s use the same 2.40GHz uncore clock, while the i3s run it at 2.13GHz and the Clarkdale Pentiums run it at 2.0GHz.

Processor Memory Latency Read Bandwidth Write Bandwidth Copy Bandwidth
Intel Core i7-975 45.5 ns 14379 MB/s 15424 MB/s 16291 MB/s
Intel Core i5-750 51.5 ns 15559 MB/s 12432 MB/s 15200 MB/s
Intel Core i5-661 76.4 ns 9796 MB/s 7599 MB/s 9354 MB/s
AMD Phenom II X4 965 52.3 ns 8425 MB/s 6811 MB/s 10145 MB/s
Intel Core 2 Duo E8600 68.6 ns 7975 MB/s 7062 MB/s 7291 MB/s

 

Here’s where things get disgusting. Memory latency is about 76% higher than on Lynnfield. That’s just abysmal. It’s also reflected in the memory bandwidth scores. While Lynnfield can manage over 15GB/s from its dual-channel memory controller, Clarkdale can’t break 10. Granted this is higher than the Core 2 platforms, but it’s not great.

What we’re looking at is a Nehalem-like CPU architecture coupled with a 45nm P45 chipset on-package. And it doesn’t look very good. If anything was going to hurt Clarkdale’s performance, it’d be memory latency.

Index Clarkdale: The Perfect Home Theater PC
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  • SydneyBlue120d - Tuesday, February 09, 2010 - link

    The Intel G9650 doesn't exist, what You're referring is Intel G6950
    http://ark.intel.com/Product.aspx?id=43230">http://ark.intel.com/Product.aspx?id=43230
    Reply
  • puterfx - Wednesday, February 03, 2010 - link

    I've been building systems since the late 90's, mostly for others, and I'm always the last to get a decent system so I decided it was about time for me. I'm running an e6600 on a 3 yr old Intel board w/ 2g of DDR2 RAM and was wondering about the differences between C 2 quad, i3-540, i5-750 or i7-820. I priced out 3 different setups with Gigabyte boards (EP45, H57 & P55 - USB3 ver.) combined with Q8400/9300/9400 on EP45, i3-540,i5-750 and i7-820 on the H57 & P55 and 4 Gb DDR3 RAM (Crucial, Geil, Kingston)so , basically, I had 9 combinations. Excluding the i7, the price range for these builds was about $429 - $487, and I could probably do better if I tried but I was amazed that they were that close (the i7 adds another $100 but not that much improvement in performance that I can see).

    Looking at your charts, I think I can justify going with the i5-750. I have a decent video card for the occassional gaming that works pretty good for me now (I'll apply the $100 from above to a better card later) but I do a lot of spreadsheets and some photoshop and autocad so I think I'll see a better improvement there.

    Thanks again for all your articles. Very well written, understandable and thorough.
    Reply
  • KingAlexander - Saturday, January 30, 2010 - link

    I too am puzzled by the i7 870 scoring so low on the World of Warcraft chart -- it stood out to me immediately when I first read the article. I was a little surprised to not see it mentioned.

    It was suggested in another comment that this was due to the game having an issue with hyperthreading, but if that was the case shouldn't the i7 920 also have scored significantly lower than it did?
    Reply
  • Bloodx - Monday, January 25, 2010 - link

    It should be noted that this new intel system does not work
    at 1080p/24 correct. The nvidia 9400 chipset works at 1080p/24.
    So i've traded audio for skipping.
    HTPC is no better off. Sad.
    Reply
  • geok1ng - Sunday, January 10, 2010 - link

    Previous Intel IGPs managed achieve less terrible numbers in game by cheating- they didn't render all the polygons and textures. So for good measure i require side by side screenshots of the "new, better, faster and cheaper" Intel IGP.

    The idea of an Intel IGP that simply isn't horrible is SOO strange that a true review would have to go the race: benchmarks, screenshots, minimum playable settings for various games and screenshots. Something the articles on HardOCP.
    Reply
  • snakyjake - Wednesday, January 06, 2010 - link

    Why isn't the i7-860 tested in the section "Windows 7 Application Performance"?

    Without the i7-860 in the Windows 7 test section, this review is pointless.
    Reply
  • NeBlackCat - Wednesday, January 06, 2010 - link

    I was hoping to build a new always-on home server around one of these. Power miserly IGP and idle operation (for when it's only firewalling and routing) but plenty of grunt in reserve for occasional video encoding, compiling and running virtual machines.

    Looks like they missed the mark for this application, and I couldn't even adopt now and wait for the real deal CPU later, as the socket is a dead end.

    IMHO only the HTPC crowd have a reason to be excited here, but there are lots of other (cheaper) ways to get low power 1080p too.
    Reply
  • ruetheday - Friday, January 08, 2010 - link

    Let's wait and see - There are products coming which will do gpu assisted transcoding that might shift things in Clarkdale's favor. Reply
  • bongbong - Tuesday, January 05, 2010 - link

    I know for a fact that the athlon II x3s and x4s have to overclock like crazy in games to reach the same performance delta as their phenom II x3 and x4 brethren
    (coz of the 6mb cache and many games are dependent on cache)
    Ive seen gaming benchmarks on anandtech where the x3 720 matched the x4 965 when they are both overclocked to 3.8ghz.
    I was able to buy an x3 720 for only a 110 usd recently.
    So why isnt it in the benchmark comparisons?


    Reply
  • JohnMD1022 - Tuesday, January 05, 2010 - link

    $150 from microcenter. Reply

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