Power

AMD has made numerous improvements compared to the K8 core:
  • The FPU unit can be turned off when not needed
  • Clock gating is implemented much better
  • Each core can run at its own frequency (but the voltage is the highest needed by either core)
  • Power for the core and memory controller are split

We measured power consumption using two identically configured Colfax systems running Windows 2003 SP1 64-bit. The server configuration is listed below:

AMD Intel
Motherboard Supermicro H8DMU+ Supermicro X7DBE+
BIOS Revision DMU8157v3.ROM R1.3C
CPU 2 x Opteron 2350 (2.0GHz) 2 x Xeon 5345 (2.3GHz)
Memory 8GB (8 x 1GB DDR2-667) 8GB (8 x 1GB FBDIMM-667)
Hard Disk 1 x Seagate Barracuda ES (400GB) 1 x Seagate Barracuda ES (400GB)
Power Supply 700W Redundant 700W Redundant
OS Windows Server 2003 SP1, 64-bit Windows Server 2003 SP1, 64-bit

At idle, the Opteron 2350 platform uses significantly less power than the Xeon setup, a decrease of about 44%. While Intel will be able to drop its power consumption with the move to 45nm, the impact won't be great enough to close this gap. The problem here is that Intel must use FB-DIMMs which consume significantly more power than AMD's registered DDR2, short of switching memory technologies there's nothing Intel can do.

CPU Idle Load (Cinebench R10 XCPU) Performance per Watt (Cinebench Score/Watts)
Dual Opteron 2350 188W 299.9W 41.9
Dual Xeon 5345 257W 347.3W 47.4

Under load, the two are closer in power consumption with the Xeon only using 16% more total system power. Looking at performance per watt, Intel is actually ahead thanks to superior performance under the Cinebench R10 benchmark.

Fritz Chess Conclusion
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  • Phynaz - Monday, September 10, 2007 - link

    Isn't this intentionally crippling the system?
  • JohanAnandtech - Monday, September 10, 2007 - link

    No. Just check what Intel and other companies do when they submit Specjbb scores for example. With HW prefetch on, you get about 10% lower scores.
  • nj2112 - Tuesday, September 11, 2007 - link

    Was HW prefetching off for all tests ?
  • lplatypus - Monday, September 10, 2007 - link

    I thought that 2x00 series CPUs only supported one coherent hypertransport link, so would this mean that the "Dual Link" feature involving two HT links would require 8300 series CPUs?
  • mino - Tuesday, September 11, 2007 - link

    Well, maybe the changed that and all links are active (to enable setups like this) and the CPU just refuses to comunicate more than one coherent hopa away..
  • mino - Tuesday, September 11, 2007 - link

    Well, maybe the changed that and all links are active (to enable setups like this) and the CPU just refuses to comunicate more than one coherent hopa away..
  • MDme - Monday, September 10, 2007 - link

    Let the games begin!
  • Viditor - Thursday, September 13, 2007 - link

    Are you going to be re-doing the review with the shipping version (stepping BA) anytime soon?
    I'm most curious to see if the improvement of 5%+ claims are true...
  • MDme - Monday, September 10, 2007 - link

    I think Barcelona will be a success in the server world. It's performance is around 20% faster than equivalently clocked xeons with the exception of certain programs like fritz and the linpack intel library where it is around 5-10% slower. But since it scales better than the xeon chips it should negate that and increase it's lead on others as core/sockets increase. add to that it's power efficiency tweaks and aggressive pricing, AMD will be able to hold off intel in the server world.....maybe.

    With 2.5Ghz Barceys coming up that would be equivalent to around 3-3+ Ghz xeons. So AMD was right that they need to get to 2.6 Ghz....AMD needs to ramp up clock to get the highest-end performance crown, but for now, their offering offers a nice balance of performance and power efficiency for the price.

    Now time for the Phenom to get it's act together.
  • TA152H - Monday, September 10, 2007 - link

    The article should have mentioned the performance penalty Intel chips are suffering from with regards to FB-DIMMS. While it's true they should be benchmarked in servers with with memory, it's also widely rumored that they are going to be offering choices in the near future. This memory has a really big impact on a lot of benchmarks, so when looking towards the future, or desktop, it's important to keep in mind the importance of Intel using different memory. I don't think even Intel is stubborn enough to stick with this seriously slow, and power hungry memory. Maybe as a choice it's fine, but it must be clear to them that offering something else as well as FB-DIMMs is very desirable in the server space. Then again, look at how long they stuck with Rambus.

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