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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Proteusza - Thursday, January 8, 2009 - link
No, I said I hoped it could at least compete with a Core 2 Duo.if its too much to hope that a 2 year younger, 758 million transistor CPU could compete clock for clock with a first gen Core 2 Duo, then AMD has truly fallen to new lows. It has more transistors than i7, and yet it cant compete with a Core 2 Duo let alone i7. What happened to the sheer brilliance of the A64 days? It could beat the pants off any Pentium 4. Now the best AMD can do is barely acceptable performance at a higher clockspeed than Intel needs, all the while using a larger die than Intels.
This keeps them in the game, but it means I wont bother buying one. Why should I?
coldpower27 - Thursday, January 8, 2009 - link
Those days are over, their success was also contigent with Intel stumbling a bit and they did that with P4, with Intel firing on all cylinders, AMD at acceptable is just where they are supposed to be.Denithor - Thursday, January 8, 2009 - link
It wasn't so much of a stumble, more like a face-plant into a cactus. Wearing shorts and a tshirt.Intel fell flat with Netburst and refused to give up on it for far too long (Willamette -> Northwood -> Prescott -> Cedar Mill). I mean, the early days of P4 were horrible - it was outperformed by lower-clocked P3 chips until the increased clockspeed was finally too high for architectural differences to negate.
Into this mix AMD tossed a grenade, the A64 - followed by the X2 on the same architecture. With its IMC and superior architecture there was no way Netburst could compete. Unfortunately, AMD hasn't really done anything since then to follow through. And even today's PII isn't going to change things dramatically for them, they're still playing second fiddle to Intel's products (which means they're forced into following Intel's lead in the pricing game).
JKflipflop98 - Thursday, January 8, 2009 - link
Damn it feels good to be a gangsta ;)Kob - Thursday, January 8, 2009 - link
Thanks for the meaningful comparison with such a wide range of processors. However, I wonder why the benchmarks are so much tilted toward the graphics/gaming world. I think that many in the SOHO world will benefit from test results of other common applications/fields such as VS Compilation, AutoCAD manipulation, Encryption, simple database indexing and even a Chess game.ThePooBurner - Thursday, January 8, 2009 - link
In the article you compare this to the 4800 series of GPUs. I actually see this as the 3800 series. It works out perfectly. The 2900 came along way late and didn't deliver, used to much power, didn't overclock well, and was just all around a looser of a card. Then the 3800 came along. Basically the same thing, but with a die shrink that allowed it to outstretch, just enough, it's predecessor. It was the first card where they got the mix right. After that came the 4800 with a big boost and even more competition. This is what i now see happening with the CPU line. The Phenom 1 was the 2900, and the Phenom II is the 3800. Getting the mix right and getting ready for the next big swing. But, as you point out, Intel isn't likely to sit back, and we can all agree that they are a much different competitor than Nvidia is.Denithor - Thursday, January 8, 2009 - link
...and just like the 3800 series, it falls just short of the target.Remember? The 3870 couldn't quite catch the 8800GT and the 3850 couldn't quite match the 9600GT. While they weren't bad cards, they unfortunately also didn't give AMD the muscle to set pricing where they wanted it, instead they had to put pricing in line with how nVidia priced their offerings.
Same is happening here, with AMD pricing their chips in line with Intel's Q9400/Q9300 processors. And they may have to drop those prices if Intel cuts the Q9550/Q9400 down another peg.
Griswold - Friday, January 9, 2009 - link
Rubbish theory. First of all, these cards were actually available whereas the 8800GT was in extreme short supply and thus much more expensive for many weeks, even into 2008, because it literally made everything else nvidia had to offer obsolete. I couldnt get one and settled for a 3870 for that reason.Secondly, the 9600GT? Do you realize how much later that card came to the game than the 3850? It hit the market near the end of february. Thats almost 3 months after the launch of the 38xx part.
The whole comparison is silly.
ThePooBurner - Friday, January 9, 2009 - link
The 3800 line wasn't ever meant to beat the 8800 line. It just wasn't in the cards. It's purpose was to get the reins back under control. Cut the power and get back to a decent power/performance ratio as well as get equal power to a previous generation in a smaller package to help improve margins. It was a stage setter. From the first time i read about it i knew that it was just a setup for something more, something "bigger and better" that was going to come next. And then the 4800 came along and delivered the goods. I get this same feeling reading about the Phenom II. It's setting the stage. Getting about the same power (a small bump, just like the 3870 over the 2900) in a smaller package, a better power/performance ratio, etc.. This is simply a stage setting for the next big thing. The next CPU from AMD after this one is going to deliver. I'm sure of it.Kougar - Thursday, January 8, 2009 - link
If you tried Everest and Sandra, what about CPU-Z's cache latency tool? It's not part of the CPU-Z package anymore, but they still offer it. Link: http://www.cpuid.com/download/latency.zip">http://www.cpuid.com/download/latency.zipI thought this tool was very accurate, or is this not the case? It even detected the disabled L3 cache on a Northwood that turned out to be a rebadeged Gallatin CPU.