Closer Look at Phenom II X3
I have to say right away that the circumstances forced AMD to deliver Phenom II X3 processors to the market. K10 microarchitecture implies that there is a monolithic quad-core die. Phenom II processors manufactured with 45nm process have a pretty big die: 258sq.mm. The production cost for these dies is quite high. For the sake of comparison I can say that Intel uses semiconductor dies that big only in their Nehalem CPUs positioned for the upper price segment. But unfortunately, the current market situation forces AMD has to sell processors at a much lower price, giving up a significant share of the revenue. Putting partially defective dies to good use is a forced measure in this case, as they need to increase the production profitability. That is why we shouldn’t be surprised that Phenom II X3 series emerged so quickly.
Let’s take a closer look at the Phenom II X3 semiconductor die:
Four computational cores take a little over half of the die size that is why the defect is more probable to be found in one of the cores rather than cache-memory. Therefore, AMD offers not only Phenom II X4 800 solutions with smaller L3 cache memory that we have already reviewed before, but also Phenom II X3 700, where one of the cores is disabled right from the start. Thanks to both these series semiconductor dies that for some reason cannot be used in fully-functional Phenom II X4 900 processors will not go to waste.
At the same time, it is pretty funny that the “limited” Phenom II X3 700 processors have L3 cache memory of maximum possible size that is why triple-core AMD processors boast a larger L3 cache than their quad-core counterparts from Phenom II X4 800 series. However, it is not the first time that we are missing the logics in AMD processor characteristics. Another funny inconsistency is that Socket AM3 processors including “limited” Phenom II X3 700 and Phenom II X4 800 clock integrated North Bridge and HyperTransport 3.0 bus at 2.0GHz frequency. At the same time, top Phenom II 940 and 920 models are compatible only with Socket AM2/AM2+ platforms and use 1.8GHz North Bridge and HyperTransport 3.0 bus.
The complete list of currently selling 45nm AMD processors with their specifications is given in the table below. It shows that AMD Phenom II model numbering system that used to be so well-balanced and logical starts getting messed up.
Just like with Phenom II X4 800, one of the key peculiarities of Phenom II X3 700 processors is their Socket AM3 form-factor that is compatible with Socket AM2+ and Socket AM3 mainboards supporting DDR2 and DDR3 SDRAM. However, we have already talked about the new AM3 processor socket and memory controller in our previous review, so now let’s move right to the features and peculiarities of the AMD Phenom II X3 720 processors that we received in our lab:
Phenom II X3 720 is the top triple-core AMD processor available today. One of its most important features that hasn’t been mentioned in the table above is the fact that it belongs to the Black Edition series positioned for computer enthusiasts. It means that Phenom II X3 720 has an unlocked clock frequency multiplier that allows easy overclocking.
When we analyze the specifications of AMD’s triple-core processors, we need to point out that the calculated maximum heat dissipation for Phenom II X3 is set at 95W, which is the same as for Phenom II X4 800 series CPUs. And it immediately suggests that from the power-saving standpoint triple-core AMD processors will lose seriously to the opposing dual-core Intel solutions with only 65W TDP. In other words, AMD’s triple-core concept looks very promising in terms of performance in multi-threaded environments, but the energy efficiency matters seem to become secondary in this case.
However, it is no big news to us. CPUs with three computational cores are not a new trend in the processor market. For almost a year first-generation triple-core Phenom X3 processors based on 65nm semiconductor dies have been available to users. We have already studied all highs and lows of the triple-core CPU design with their help.
That is why there is nothing surprising about the way the triple core Phenom II X3 720 is recognized by the operating system and interacts with applications. The diagnostic CPU-Z utility sees all three cores, too. Here is a screenshot for your reference:
This utility sees Phenom II X3 720 processor as a member of the Deneb family, and although it is quite logical considering that it is based on the same semiconductor die as the 45nm quad-core CPUs, its formal codename is Heka. The manufacturer uses this particular name for their triple-core solutions, however, CPU-Z doesn’t detect this.