Power Consumption

Given that AMD reduced power consumption a bit alongside the move to Socket-AM2, we wanted to see how the new chips compared to the latest CPUs AMD had sent us prior to the launch. So we pitted our last Socket-939 sample, the Athlon 64 FX-60, against the two new Socket-AM2 samples we just received: the Athlon 64 FX-62 and the X2 5000+. Remember that the FX-62 actually carries a 125W TDP rating, so it shouldn't be any cooler than previous CPUs, but the X2 5000+ is a new 89W part.

There are inevitably going to be power differences between the Socket-AM2 and Socket-939 motherboards we used, but unfortunately there was no way to isolate them from the comparison as we are measuring total system power consumption.

System Level Power Consumption at Idle

System Level Power Consumption under Full Load

Under full load, the X2 5000+ does appear to be a bit cooler than the Socket-939 FX-60. We've seen in the past that the 1MB vs. 512KB of cache doesn't really result in any significant difference in power consumption, so it looks like the overall decrease in power consumption is because of the improvements in production AMD has implemented at Fab 30. It is worth noting that the Pentium Extreme Edition 965 consumes just as much power as the FX-62, thanks to its 65nm manufacturing process. Even so, we still can't wait for Intel to drive its power consumption levels even lower later this year.

The Odd Multiplier Issue Final Words
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  • soydios - Tuesday, May 23, 2006 - link

    AMD motherboards are less expensive because they don't have to put in a memory controller.

    AMD processors are more expensive for 2 reasons:
    - integrated memory controller takes up more die space (offset by cheaper motherboard)
    - AMD is still using 90nm on 200mm wafers, while Intel is using 65nm on 300mm wafers (Intel gets more CPUs per wafer bigtime)
    Reply
  • peternelson - Tuesday, May 23, 2006 - link


    Sempron AM2 can do memory up to DDR2-667

    Dualcore AM2 can do memory up to DDR2-800

    However, PLEASE CHECK SINGLE CORE MEMORY SPEED (multiplier issues aside) which you say limited to 667 whereas I got the impression they can also do 800 like dualcores. Correct as necessary.
    Reply
  • smitty3268 - Tuesday, May 23, 2006 - link

    I accidentally hit the "not worth reading" button, so I'm writing this comment to undo it :) Reply
  • fikimiki - Tuesday, May 23, 2006 - link

    There are a couple of reasons for that:
    - K8L photo had a Z-RAM implemented, so they are using this kind of cache for a quite long time.
    - Shared L3 should help Athlon64 in matching Super-Pi and overall performance.
    - Usage of Z-RAM will reduce cache die size by 75% with no architectural changes.

    So FX-64 to beat fastest Core 2 just needs 4MB of cache...
    Easy trick but can be useful to survive till 65nm production...
    Reply
  • Questar - Tuesday, May 23, 2006 - link

    quote:

    K8L photo had a Z-RAM implemented, so they are using this kind of cache for a quite long time.


    It's not going to be Z-RAM. Z-RAM won't even be in K8L.

    “We’ve looked at data from Innovative Silicon and it looks very promising. We still need to assure ourselves that this will work in our own application. We need to see how it scales and we need to make our own test vehicles,”

    Jones, an executive experienced in intellectual property licensing, also declined to comment on AMD’s timetable for introduction of Z-RAM but offered a more general perspective. “In the past it has been two years from when you sign a deal to when it is in production.”


    http://www.eetimes.com/news/latest/showArticle.jht...">http://www.eetimes.com/news/latest/showArticle.jht...
    Reply
  • munky - Tuesday, May 23, 2006 - link

    I think the June trick AMD will pull out is the Clearspeed coprocessor. It definitely won't affect many users, but for those who do invest in the technology, it could provide a decent boost in number crunching power. Reply
  • peternelson - Tuesday, May 23, 2006 - link


    Clearspeed are working on being one acceleration solution, yes, but the already launched acceleration on socket 940 is companies offering plug in Xilinx4 FPGA on hypertransport.

    I hope that gets re-engineered onto socket F pretty quickly. We may see announcements once socket F is actually launched in July.
    Reply
  • 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.. Reply
  • 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
    Reply
  • 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.
    Reply

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