The Question on Everyone's Mind: Is AM2 Faster?

We've structured this CPU review a little different than in our past, organizing the content into answers to a series of questions that we had about Socket-AM2 and the performance of the platform. The first question on everyone's mind is, of course, is Socket-AM2 any faster than Socket-939. When we previewed AM2 we concluded that no, it wasn't, however we were using pre-release hardware and it was possible that the performance had changed since then. But the following statement from AMD pretty much confirmed exactly what we expected:

"A fair expectation for performance gain from 939-pin to AM2 is about 1% or more across various application-based benchmarks. That assumes equal model numbers for processors and an equal configuration. This also assumes premium memory is used for each configuration."

With AMD telling us that we should expect about a 1% increase in performance, it doesn't look like Socket-AM2 will have much to offer in the way of performance. Of course we needed to confirm for ourselves, and the table below shows just that:

Benchmark - Athlon 64 X2 4800+ Socket-939 (DDR-400) Socket-AM2 (DDR2-800) % Advantage (Socket-AM2)
Cinebench 9.5 Multi-Core Rendering Test 660 658 0%
3dsmax 7 2.79 2.78 0%
Adobe Photoshop CS2 183.2 s 180.2 s +1.6%
DivX 6.1 54 fps 54 fps 0%
WME9 42.2 fps 42.7 fps +1.2%
Quicktime 7.0.4 (H.264) 3.12 min 3.10 min +0.1%
iTunes 6.0.1.4 (MP3) 35 s 35 s 0%
Quake 4 - 10x7 (SMP) 133.1 fps 138.6 fps +4.0%
Oblivion - 10x7 56.1 fps 58.0 fps +3.3%
F.E.A.R. - 10x7 114 fps 116 fps +1.8%
ScienceMark 2.0 (Bandwidth) 5397 MB/s 6844 MB/s +27%
ScienceMark 2.0 (Latency 512-byte stride) 47.3 ns 42.72 ns +9.7%

The numbers we're seeing here today for Socket-939 vs. Socket-AM2 are virtually identical to what we saw last month in our preview. Socket-AM2 doesn't appear to offer any tangible improvement in performance except for within certain games and of course in the memory bandwidth and latency tests. Thankfully, on final hardware, we're at least not seeing any drop in performance.

The good news is that if you've just invested in a new Socket-939 platform, you're not leaving any performance behind by not having an AM2 system. The bad news is that, for AMD, the only performance increases this launch will bring are because of the speed bumps of the Athlon 64 FX-62 and the X2 5000+.

Energy Efficient AM2 CPUs Does AM2 Reduce the Impact of L2 Cache Size?
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  • darkdemyze - Tuesday, May 23, 2006 - link

    z-ram isn't due for AMD procs for quite some time, I doubt this is their plan for June..
  • mlittl3 - Tuesday, May 23, 2006 - link

    Basically this is what I said above for my guess of the "trick" AMD will use. Anand said it will only affect some high-end users, read FX series so it can't be price cuts as some have suggested (that would effect everyone). Adding L3 cache is the only performance improvement I can think of that doesn't require changing the microarchitecture of the cores (well at least not a big change).

    However, TDP is still an issue here as someone above suggested. I don't know how much more power it takes to run L3 cache. Last time AMD did it was on K6 and power wasn't really measured back then.

    By the way, please ignore Questar's comment below about z-ram being pig slow. I really don't think he knows what he is talking about. /shields eyes from incoming Questar flame
  • johnsonx - Wednesday, May 24, 2006 - link

    K6-III did not have L3 cache. It had L2 cache, making the cache that all socket-7 boards had then an L3 cache.

    So, let's stop saying things like 'AMD hasn't done L3 cache since K6-III', etc.
  • mino - Wednesday, May 24, 2006 - link

    Well, IMHO the point is AMD has used exclusive 3-level cache structure in the past so they have som experience with thi arrangement.
  • Questar - Tuesday, May 23, 2006 - link

    No flame here, look it up for yourself.

    Z-RAM has high capacitive loading, which results in slow speed.

    At 4MB it'll run half the speed of SRAM.
  • Questar - Tuesday, May 23, 2006 - link

    Large amounts of Z-RAM are pig slow.
  • Ecmaster76 - Tuesday, May 23, 2006 - link

    Seriously, the one area an Athlon X2 would be bandwidth starved and does it get tested in the preview? NO
    In the review? NO

    How long ago did we know that the K8 was not bandwidth limited in single application usage? YEARS


    So yeah, DDR2 din't increase the 3dMark, big surprise
  • mlittl3 - Tuesday, May 23, 2006 - link

    I think 3dMark06 is multithreaded now so all available cores and bandwidth should be used within the limits of the program. I could be wrong about this however.
  • Ecmaster76 - Tuesday, May 23, 2006 - link

    3Dmark06 is almost completely GPU limited. The 3Dmark CPU score did increase a bit, but I really was referring to graphics benchmarks in general.
  • cscpianoman - Tuesday, May 23, 2006 - link

    I was just noticing the performance differences between the FX and the EE. In some cases the FX tromps the EE by "gasp" 30%! In other cases the EE makes it's mark. This is part of the reason I am skeptic on Conroe. Yeah it's good. But I always take what Intel, or AMD for that matter, with a grain of salt. Just today we saw the 30% advantage translate down to about 15%. This seems just like any other generation change where 15% is to be expected. The current hype for the Conroe is a product of Intel's excellent marketing dept.

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