AMD Phenom II X4 940 & 920: A True Return to Competition
by Anand Lal Shimpi on January 8, 2009 12:00 AM EST- Posted in
- CPUs
The Phenom Inspired, Core i7-like, Phenom II
Want to hear something funny? When AMD launched the original Phenom, it was a unique looking architecture, something AMD touted as a significant advantage due to its "native" monolithic quad-core design (four cores, one die). I often argued that it wasn't an advantage, simply because the performance numbers didn't back up AMD's claims. AMD never won a real world desktop benchmark because of the monolithic quad-core design.
Intel followed up with Nehalem (Core i7), a microprocessor that had a very Phenom-like cache hierarchy (four cores, private L2 caches, one large shared L3 cache), but with much better performance.
Phenom II builds upon the same architecture as the original Phenom, hardly changed, but improves on a few key limitations. This isn't a new microarchitecture, this is a 45nm shrink of Phenom. In a sense, AMD gave up on improving the original Phenom. Early on after Phenom's release AMD went head in the sand and did whatever was necessary to make the 45nm transition perfect. Deneb, as it was called internally, had to succeed - because AMD as a company wasn't going to survive on the backs of the GPU division forever. It's somewhat ironic that Intel was able to execute a better Phenom-like microarchitecture before AMD.
| Processor | AMD Phenom II | AMD Phenom | Intel Core i7 | Intel Core 2 Quad Q8xxx/Q9xxx |
| Manufacturing Process | 45nm | 65nm | 45nm | 45nm |
| L1 Cache | 64K + 64K per core | 64K + 64K per core | 32KB + 32KB per core | 32KB + 32KB per core |
| L2 Cache | 512KB per core | 512KB per core | 256KB per core | 2x3MB, 2x4MB or 2x6MB |
| L3 Cache | 6MB | 2MB | 8MB | - |
| Transistor Count | 758M | 450M | 731M | 456M (6MB/8MB L2) or 820M (12MB L2) |
| Die Size | 258 mm2 | 285 mm2 | 263 mm2 | 164 mm2 (6MB/8MB L2) or 214 mm2 (12MB L2) |
The above chart details the specifications for the current AMD and Intel quad-core offerings, and here we see a problem. Phenom II and Core i7 are around the same die size and have similar transistor counts, yet Core i7 sells for $284 - $999 while Phenom II sells for $235 - $275. The part that Phenom II actually competes with is the Core 2 Quad Q9400 (and perhaps the Q9550; more on that later), and that's a ~36% smaller die. This is the downside to AMD's pricing strategy; while it's great for consumers it's not particularly great for AMD's profit margins. The other thing to keep in mind is that at 214 mm2 Intel has an entire line of quad-core processors that, in theory, could be moved down the price list if the price wars of 2008 were to continue into 2009.
The move to 45nm was severely needed as you can see by the table above. AMD and Intel seem to agree on the right way to build a quad-core processor today: four cores with individual L2 caches (or one shared L2 per two cores on Intel) behind a large global L3 cache. Intel, however, waited until the 45nm transition was complete to move to that sort of an architecture in order to outfit the chip with a large enough L3 cache. AMD jumped the gun early with Phenom and was forced to limit its L3 cache size to 2MB on 65nm. Finally, with the move to 45nm, Phenom II boasts a 6MB L3.
The transistor counts of Phenom II and Core i7 are surprisingly close, as are the die sizes. The two chips are designed completely differently, but the end result is similarly sized processors. Note that both Phenom II and Core i7 are too big for high volume mainstream markets; the die size would need to be around half of what it is now to address those markets. AMD and Intel will do so by introducing dual (or triple in the case of AMD) core versions at 45nm and then transitioning almost exclusively to quad-core at 32nm.
Phenom II also marks AMD's return to the >$200 CPU market. The two parts launching today are the Phenom II X4 940 and the Phenom II X4 920, priced at $275 and $235 respectively.
| Processor | Clock Speed | Uncore Clock | L2 Cache | L3 Cache | TDP | Price |
| AMD Phenom II X4 940 | 3.0GHz | 1.8GHz | 2MB | 6MB | 125W | $275 |
| AMD Phenom II X4 920 | 2.8GHz | 1.8GHz | 2MB | 6MB | 125W | $235 |
| AMD Phenom 9950 | 2.6GHz | 2.0GHz | 2MB | 2MB | 140W | $174 |
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Shadowmaster625 - Friday, January 16, 2009 - link
Why didnt you include an overclocked E5200 in the testing?!?!?!omg this is horrid. How do these $230-$270 CPUs compare to an $85 E5200 coupled with a $105 Gigabyte GA-EP45-UD3R? That combo will easily overclock to 3.8 Ghz on stock cooling. CPU, mobo + RAM all for less than the cost of a Phenom II. And better performance too.
Reynod - Monday, January 12, 2009 - link
Another excellent article Anand.Would you be able to write a short piece on the AM3 socket and the "likely" impact on performance once you have some samples please?
R4F43LZiN - Saturday, January 10, 2009 - link
I wanted to see some Phenom II overclocked gaming benchmarks...zagortenay - Saturday, January 10, 2009 - link
To correct my mistake in above post:"And check the link of very respectable "Guru of 3D" yourself, X4 940 beats Core i7 920 in higher resolutions." Not Core i7 940.
zagortenay - Saturday, January 10, 2009 - link
Great comments Aranthos! AMD did a great job with Phenom II, no doubt about that.Anandtech review is kind of fair and balanced when it comes to giving the final verdict, but the tests are deceiving and unfair as usual.
First of all, as somebody else has already pointed out, they used an average mobo to test Phenom II, while they used expensive enthusiast level mobos for Core2 Quad and Core i7 (230 and 250 Dollars respectively). They could not find an Asus M3A79-T (which is much cheaper at 185$) There is no excuse for that! Either a deliberate move not to show what Phenom II can deliver at its best, or Anand needs to learn a lot from us. Just check the below link to see the performance difference between 790GX and 790FX. Quite some performance difference in some benchmarks and consider that it is still a close competition with an average AMD motherboard.
There IS a difference apparently: http://www.legitreviews.com/article/795/5/">http://www.legitreviews.com/article/795/5/ and it would change some conclusions
And now introducing a classic: Why Core2 Quads run on DDR3 (Yeah, all Core2 Quad users definitely switched to DDR3, lol!) and Phenom IIs run on DDR2? To show the best of Core 2 Quads... So what happens if DDR2 is used also on Core 2 Quads? See yourself below. X4 940 beats Q9550 most of the time and even Q9650 in some applications.
http://www.bit-tech.net/hardware/2009/01/08/amd-ph...">http://www.bit-tech.net/hardware/2009/0.../amd-phe...
I wander what trick they will do with RAMs, when Phenom II AM3 (with DDR3) comes this February.
Anand says X4 940 trails Q9650 and by 28.4% when it comes to Far Cry 2. Is it so? Or? Check the above link again. Even with DDR3 RAMs Q9650 leads by only 4.4%. With DDR2, X4 940 leads this time, with a little margin. Same resolution! Who to beleive?
And check the link of very respectable "Guru of 3D" yourself, X4 940 beats Core i7 940 in higher resolutions. He he!
http://www.guru3d.com/article/amd-phenom-ii-x4-920...">http://www.guru3d.com/article/amd-phenom-ii-x4-920...
So what? Don't get fooled, don't get deceived by the "big brother connections".
Final words: Yes I am a fan boy and I don't pay a penny for Intel!
Aranthos - Saturday, January 10, 2009 - link
I wonder why so many people keep saying "What happened to the AMD from the Athlon64 era? It was whupping Intel!" etc.That AMD is still here. The same AMD that so long ago brought us Hypertransport, the integrated memory controller, native dual-core and the like brought us native quad-core and a three level cache heirarchy a full year before Intel did either. As it turned out, Intel did it better - a fact with which I won't even try to argue. However, AMD is still working.
P1 flopped. It was the most hyped chip in years, and brought all sorts of false promises. All Deneb promised was better overclocking, lower power consumption and more clock-for-clock performance. It did all 3.
I'm not going to say Intel ripped off AMD by using an IMC and a HT-esque high speed interconnect. Granted, AMD did it first, but Intel would have ended up doing it ANYWAY because it is a good idea.
Back to the original topic - we still have the old AMD with us. They're still innovating as always. But, we have a new Intel. One that isn't peddling crappy Netburst chips. New Intel is going out guns blazing, and they have the money to make sure that another P4 doesn't happen.
AMD got lucky back in the P3 -> P4 era. They're gonna have to either pull out a win of epic proportions, or stick to razor thin margins on their chips. Intel has seriously deep pockets, and can easily afford to destroy AMD's prices.
i7 is epic win. But I'm buying a Deneb anyway. Yeah, people are gonna call me a fanboy, and so what. I'm buying a chip made by a company that is facing a company over 50x their size. While they're not a little family run business, I will support them to their dying breath because they need every sale they can get. I like high performance as much as the next guy, but if buying higher performance (in my case at a higher price [I have an AM2+ motherboard]) puts the business a step closer to being one-sided, then Intel can suck it. They don't need my money.
Mathos - Saturday, January 10, 2009 - link
Well, it's not quite a 4800 series equivelent release this time. More like being around the same as the 3800 series was. A good improvement over the hd2000 series cards, in this case a good improvement over the phenom 1.On the other hand I am wanting to see what will happen with the AM3 versions. Should improve scores quite a bit on anything that likes memory speed and bandwidth. I'm also wondering what other optimizations will come with AM3. Gonna wait for that, since I should be getting another nice quarterly bonus around the time those come out. Use a pII 945 on my old k9a2 plat till I can get an AM3 board and DDR3 memory.
Maroon - Saturday, January 10, 2009 - link
This was a great step forward by AMD. After the Phenom flop they had to transition successfully to 45nm or basically fold. They have done that. AMD doesn't have the resources to compete with Intel on the highend right now, but with this release they can compete in the mainstream market where most processors are sold.They're using the same strat that worked for the 4xxx series video cards, performance per dollar.
Megaknight - Friday, January 9, 2009 - link
Have the Intel fanboys noticed that they're comparing a DDR 2 Phenom II to a DDR 3 i7? I know AMD will be slower anyway, but it should close the gap a bit, right?aeternitas - Friday, January 9, 2009 - link
Are you serious? DDR3 might be able to give AMD an advantage overall compared to the C2. But then going DD3 and spending that much money, you might as well go i7 anyway. (unless you're a fanboy)Seriously guys, if you're going t go around comparing P2 to the i7, you need to focus on price! Else you'll look really bad.
P2 is against C2. End of story. You cant sit around theorizing some magical item is going to get a P2 anywhere close to the i7.
Stop defending AMD. They have 18 months of catchup to do and dont need pats on the back and excuses from people like you. They have a good chip and alot of good things in the chip that they dont need to do in the future as they come up with new architecture.