45nm and Low Power Consumption

Built on a 45nm process, Phenom II is finally using the same feature size as Intel’s processors. Intel’s 45nm caches are a bit smaller than AMD’s, but it’s no longer a 65nm vs. 45nm playing field - things are much more even. However, AMD and Intel’s approaches to 45nm differ considerably.

Circuits are placed on silicon wafers through the use of photolithography. Light is shone on a mask, and the light then makes it through the mask and etches the circuits on the silicon wafer. The wavelength of light used determines the minimum feature size of the circuits on the wafer. By itself, 193nm wavelength deep ultra-violet light is only useful for circuit feature sizes down to 50nm. To reach 45nm and beyond you need to do a little more.

AMD uses immersion lithography, which places a liquid between the source of the light and the wafer itself. The liquid increases the resolution at which the light can focus, allowing for smaller than 50nm feature sizes with currently available tools. Immersion lithography isn’t a performance enhancing feature; it’s simply one that makes it possible for AMD to manufacture at 45nm.

Intel claims that immersion lithography isn't necessary at 45nm and doesn't use it. Intel uses a technique known as double patterning but only on the gate layer of the chip. Intel’s approach requires higher mask costs but can result in a high yield 45nm chip without the use of immersion lithography. AMD’s approach should be more cost effective initially since you have to create fewer masks, but Intel’s scale of 45nm production should help offset that. For what it's worth, the double patterning has been in use since Intel's 65nm process.

Remember Intel’s high-k + metal gate transistor announcement? That’s still a feature advantage that Intel holds at 45nm. The new transistors make sure that current doesn’t flow when it’s not supposed to, reducing power consumption.

The two processes, despite both being 45nm, are different enough that they aren't the same despite having similar feature size - but comparing manufacturing processes is beyond the scope of this article.

A Power Efficient Phenom?

When Phenom first hit, not only was it underperforming, but it also drew far too much power. Combine that with a CnQ mode that robbed users of performance and you ended up with a CPU that was hardly power efficient. Just like the cache deficiency, Phenom II fixes this.

With Core i7, Intel developed power gate transistors that can completely shut off an individual core that’s not in use. Intel’s cache hierarchy is inclusive so any data stored within a core’s L1 and L2 caches is already duplicated in the L3 cache; if a core isn’t in use it can be shut down and there’s no need to wake it back up until it’s needed again.

Remember, Phenom II isn’t a complete redesign, so AMD couldn’t work on a similar technology. Despite that, idle power in Phenom II is greatly improved. When a single core is idle, the contents of its L1 and L2 can be flushed out to L3, allowing the processor to halt the clocks to that core - thus reducing power. The core will still consume leakage power, but it’ll be far less than if it were running at the lowest p-state. Intel introduced something similar back in the Conroe days, except data from L1 was pushed out to L2 before the core was powered down since there was no L3. Nehalem still has the ultimate in idle power thanks to Intel’s power gate transistors, but as you can see below Phenom II’s idle numbers are quite impressive.

Processor Idle Power Load Power
AMD Phenom II X4 940 (3.0GHz) 109.6W 189.7W
AMD Phenom 9950 BE (2.6GHz) 124.2W 210W
AMD Phenom X3 8750 (2.4GHz) 127.5W 210W
AMD Athlon X2 6400 (3.2GHz) 101W 195W
Intel Core i7-965 (3.2GHz) 99W 199W
Intel Core i7-920 (2.66GHz) 95W 168W
Intel Core 2 Extreme QX9770 (3.2GHz) 135W 219W
Intel Core 2 Quad Q9400 (2.66GHz) 126W 174W
Intel Core 2 Quad Q8200 (2.33GHz) 134W 168W
Intel Core 2 Duo E8600 (3.33GHz) 124W 157W

Note that while Penryn’s idle power isn’t nearly as low as Phenom II, this has more to do with Penryn’s lowest operating frequency. Phenom II’s minimum p-state is only 800MHz, compared to 2.0GHz on Penryn. Load power is also impressive, not quite Nehalem impressive but definitely competitive with Penryn at least.

In load power, Penryn still has the advantage. The Q9400 draws 174W compared to 190W for the Phenom II X4 940. The Core i7 is still the most power efficient of the two, as the i7-920 draws less power and is faster than the Phenom II X4 940.

Finally, Cool 'n' Quiet You Can Use Socket-AM2, AM2+ and AM3: Backwards Compatibility
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  • rudolphna - Thursday, January 08, 2009 - link

    Hey anand, do you think you could grill AMD and see if you can get out of them which chips will be made at the upcoming Malta, NY fab facility? Will it be PII or maybe bulldozer? Reply
  • mkruer - Thursday, January 08, 2009 - link

    Anand, I do alot of paring and although the recovery rate is good, i would like to see the results for creating a par2 file. Reply
  • Natfly - Thursday, January 08, 2009 - link

    I'm glad AMD is somewhat competitive in the quad core realm but I just cannot get over how blindingly fast the Core i7s are. It is incredible.

    I hope AMD can make it through, for consumer's (and my stock's) sake. This is a step in the right direction.
    Reply
  • xusaphiss - Thursday, January 08, 2009 - link

    Come on, guys! I like a competitive market as much as the next guy but AMD is a whole generation behind. They should have had these when the 45nm C2s came out!

    AMD is lapped!

    It's time for them to die!

    CPU standards will only go down if they actually resort to third-party distribution!

    Their video cards are always run hotter than NVIDIA and just less stable and overclockable. The only way they was able to stay alive in the race was pitting two of their GPUs against one on one board. NVIDIA hasn't even begun using DDR5 yet!

    Intel and NVIDIA is not really receiving competition from AMD. AMD is just lowering standards.

    Reply
  • ThePooBurner - Saturday, January 10, 2009 - link

    PLAYSTATION THREE is that you? Reply
  • aeternitas - Thursday, January 08, 2009 - link

    We would not of had C2D for years, if not for AMD. Please sit down your logic is flawed. Reply
  • Kroneborge - Thursday, January 08, 2009 - link

    Oh, let's hope AMD doesn't die. Or you can add a couple hundred on to the price of all your favorite Intel processors lol. Reply
  • Genx87 - Thursday, January 08, 2009 - link

    This one is simply not going to cut the butter by the middle of 09. True they are cutting into the Core 2 Duo's performance advantage. It still for the most part falls short. And I didnt see this thing really challange the i7 which will be Intels flagship chip by the end of 09. I dont know about AMD's future chips. But the Phenom needs an arch replacement for AMD to compete with Intel. Reply
  • JakeAMD - Thursday, January 08, 2009 - link

    I would suggest an amazing PC experience is about far more than benchmarks or the performance of one component. Some benchmarks today are at risk of losing relevance to real application performance. For example, performance on 3DMark Vantage scores don’t necessarily translate into a better gaming performance. Also, the CPU-only approach to video processing performance is now thoroughly outmoded, as that should be offloaded to the GPU. The Dragon platform technology is really within the budgets people are affording themselves today and we’re doing a better job of serving the real needs of the PC market today. So I would ask you – Is $1000 or more worth the performance difference?
    Reply
  • Genx87 - Friday, January 09, 2009 - link

    I am looking at these gaming benchmarks which is the most intensive thing I do on my computer. My 180 dollar E8400 is cheaper and faster.

    On the server side the i7 looks more attractive for my virtualization and sql server upgrade project. Where $1000 is pennies on the dollar. Though when you factor in total system cost it is usually not even that much.

    Anyways the i7 will come down in price over the course of 09 as a consumer friendly platform is released and the cost of DDR3 falls as production ramps. So it wont cost 1000 more for an i7 system for long. And I question whether an i7 system costs that much more now.

    Reply

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