Does AM2 Reduce the Impact of L2 Cache Size?

We've already seen that Socket-AM2 doesn't really impact performance except for in games, but does the higher bandwidth memory controller reduce the impact of AMD's 1MB L2 cache parts compared to its 512KB L2 cache offerings? 

 Benchmark - Athlon 64 X2 2.0GHz Socket-939 (1MB vs. 512KB Advantage)  Socket-AM2 (1MB vs. 512KB Advantage)
Cinebench 9.5 Multi-Core Rendering Test 0.2% 0%
3dsmax 7 0.3% 0.6%
Adobe Photoshop CS2 2.7% 2.5%
DivX 6.1 0% 0%
WME9 0% 1%
Quicktime 7.0.4 (H.264) 0.9% 1.3%
iTunes 6.0.1.4 (MP3) 0% 0%
Quake 4 - 10x7 (SMP) 4.8% 3.5%
Oblivion - 10x7 7.5% 3.3%
F.E.A.R. - 10x7 8.6% 6.2%

 

In the application benchmarks there isn't really a difference in how performance scales with cache size between the two platforms, but looking at the games there is indication of a pattern that is developing.

In Quake 4, Oblivion and F.E.A.R. the 1MB L2 cache seems to make slightly more of a difference on the Socket-939 platform than on the Socket-AM2 platform.  While the 1MB cache offers a 4.8%, 7.5% and 8.6% performance advantage in those three games on the Socket-939 platform, on AM2 the advantage is cut down to 3.5%, 3.3% and 6.2% respectively.  The explanation being that with a lower latency memory controller and more available memory bandwidth, the benefits of a larger cache are reduced on Socket-AM2. 

However the differences in performance scaling that we're seeing here are small enough that once you take into account the amount of variation you can see between runs, it's not really worth concluding anything concrete based on this data.  What we do see here is a trend of the 1MB L2 cache parts doing less on Socket-AM2 than on Socket-939 (another way of looking at it is that the 512KB are doing better on AM2 than they did on 939), but the margins are small enough that we can't really say for sure what is causing the trend.

Once again, the trend only seems to impact games, as the other application tests we've run appear to be basically unaffected. 

The Question on Everyone's Mind: Is AM2 Faster? How Does the New 4000+ Stack Up?
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  • jmke - Wednesday, May 24, 2006 - link

    here ya go

    quote:

    Dual-Channel DDR2-800 on AMD Athlon 64 X2 "AM2" — the First Test Results of the New Integrated Memory Controller in RightMark Memory Analyzer


    http://www.digit-life.com/articles2/mainboard/ddr2...">http://www.digit-life.com/articles2/mainboard/ddr2...
    Reply
  • Xenoid - Tuesday, May 23, 2006 - link

    Ok so AM2 is AMD's offering for 2/4 06.

    The article title mentions same performance, faster memory, lower power. Wouldn't faster memory (in this case, ddr2) net a higher performance than what we're seeing here? Why is AMD bothering with DDR2 if it's not a significant improvement? If the power usage is so low, does this mean we can overclock a lot easier? I never understood the huge deal behind power usage on a cpu.
    Reply
  • coldpower27 - Wednesday, May 24, 2006 - link

    DDR production is slowing down, and DDR2 is continuing to mature, AMD does need to change to this memory type now, regardless if they like it or not.

    DDR2 also allows higher capacities, so you can probably reach 4x2Gb now as 2Gb modles are actually available on DDR2.

    Considering DDR2 biggest advanatge bandwidth, is what AMD doesn't really need more fo right now, performance improvements will be negligible.
    Reply
  • Furen - Wednesday, May 24, 2006 - link

    Also, having all that extra bandwidth available allows AMD to throw quad-core on the same socket without much problem (maybe 1H07... whatever everyone says I doubt AMD will let Intel have the quad-core advantage for a year, I'd say we'll see very low volume quad-cores as close to Intel's Kentsfield/Cloverton as humanly possible). I know we've heard that AM3 is coming next year (from, who else?, The Inquirer) but considering that the DDR3 spec is not finalized quite yet and just how slowly AMD jumped into the DDR2 bandwagon I'd say we won't see it until 2008 at the earliest. Reply
  • Axloth - Wednesday, May 24, 2006 - link

    I think there is also marketing side. There are lots of people "unaware" of ddr1-ddr2 comparison. And they probably think that ddr2 "must" be better than ddr1 because of that that "2". Like: ddr2 is upgrade or next generation of ddr1 so its gotta be much faster. Also, they might go for intel because intel uses ddr2 and amd only ddr1... And they think intel's better thanks to ddr2, disregarding cpu qualities of both amd and intel. Reply
  • pzkfwg - Tuesday, May 23, 2006 - link

    If DDR2-800 barely beats DDR-400, I was wondering if the AM2 socket could actually be slower than 939 DDR-400 when using DDR2-667 !?! Knowing that a very large amount of people would buy cheaper AM2 system with DDR2-667, that would be ridiculous! Reply
  • mino - Wednesday, May 24, 2006 - link

    YES and NO.

    Remember most people buy generic CL3 or CL2.5 DDR400. IMHO generic DDR2-666 should be ona par with that.
    Reply
  • soydios - Tuesday, May 23, 2006 - link

    So, the X2 4200+ will not run the memory at full speed. How safe would it be to overclock from 200x11=2200MHz DDR2-733 (2200/6=366x2=733) to 219x11=2200MHz DDR2-803 (2409/6=401.5x2=803) using OCZ DDR2-800 RAM and an Asus Xpress3200 motherboard? Reply
  • Furen - Wednesday, May 24, 2006 - link

    I'd say that you can very likely get away with that overclock with pretty much every 4200+ as long as the motherboard allows you to do it. Reply
  • mino - Wednesday, May 24, 2006 - link

    Safe as safe. At least from the point it won't blow up :)

    As for stability it all depends on the motherboard.
    Reply

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