Simple Arithmetic of a Triple-Core CPU
I believe that the new AMD Phenom X3 triple-core processor family (also known as Toliman) doesn’t need a special introduction, as there is hardly anything new about it, if you look closer. These CPUs are based on the same semiconductor dies that are used in quad-core Phenom X4 processors. AMD simply blocks one of the cores in them thus making use of the “defective” chips that failed to become the base for fully-fledged quad-core processors. The mere idea of disabling part of the semiconductor die to ensure that defective high-end chips can get a second chance is not that new at all. However, until recently, AMD and Intel disabled only part of the L2 cache memory.
Phenom X4 processors differ from Intel’s quad-core ones primarily by the monolithic design, which Intel solutions are made of a pair of dual-core semiconductor dies. Therefore, the chances are quite high that there may be a defect in one of the Phenom X4 cores. And it is certainly more probable than the defect in the higher level L3 cache memory. Here Phenom’s block structure was also to AMD’s advantage. Its cores are combined at the L3 cache level, which allows taking one of the cores out of service without changing anything in the micro-architecture and semiconductor die itself.
If we compare the specifications of Phenom X4 and Phenom X3 side y side we will get even more assured that they are closely related:
AMD Phenom X4 | AMD Phenom X3 |
Codename | Agena | Toliman |
Production process | 65 nm | 65 nm |
Micro-architecture | Stars (K10) | Stars (K10) |
Cores | 4 | 3 |
Dies | 1 | 1 |
Clock frequency | 2.2-2.5 GHz | 2.1-2.4 GHz |
L1 cache | 4 x 64+64 KB | 3 x 64+64 KB |
L2 cache | 4 x 512 MB | 3 x 512 MB |
L3 cache | 2 MB | 2 MB |
Memory controller | Dual-channel
DDR2-800/1066 SDRAM | Dual-channel
DDR2-800/1066 SDRAM |
Bus | 3.6/4.0GHz HyperTransport | 3.6GHz HyperTransport |
Typical heat dissipation | 95/125 W | 95 W |
Transistors | 450 mln. | 450 mln. |
Die size | 285 sq.mm | 285 sq.mm |
Power saving technologies | C1E, Cool’n’Quiet 2.0 | C1E, Cool’n’Quiet 2.0 |
Instruction sets | ММХ, 3DNow!, SSE, SSE2, SSE3, SSE4A, x86-64 | ММХ, 3DNow!, SSE, SSE2, SSE3, SSE4A, x86-64 |
As a result, Phenom X3 processors turn out absolutely identical to their quad-core elder brothers except for the number of cores.
Today’s announcement mentions three Phenom X3 models with 2.1GHz, 2.3GHz and 2.4GHz frequencies. All these three processors are based on the new B3 stepping free from the notorious “TLB bug”. You should remember however that AMD also makes Phenom X3 processor models based on the old B2 stepping, however, they are not supplied to the retail market.
To avoid confusion in the significantly expanded line-up of Phenom processors based on new K10 micro-architecture, we decided to put together a table listing all the key features of the existing solutions:
We highlighted three new triple-core processors that will be the first Phenom X3 to become available in retail.
Note that all new Phenom X3 features 95W TDP, which indicates that they should work with a broad variety of Socket AM2/Socket AM2+ mainboards, including those from the value segment. In fact, all you need to ensure that new triple-core processors will be compatible with your mainboard is to reflash the BIOS.
The compatibility of the new Phenom X3 processors with available software seems a little bit more complicated. Since it is the first CPU with tree cores, it may face some problems with applications being unable to detect and use odd number of cores correctly. However, these individual problems will hardly become very widely spread. During our test session, for example, we haven’t had any issues, except the old versions of the SiSoft Sandra diagnostic utility that didn’t work.
Nevertheless, I would like to draw your attention to the fact that they released an update a few days ago for 32-bit Windows server 2008 and Windows Vista operating systems intended to solve problems caused by incorrect detection of the number of available cores. You can get the corresponding info regarding this update from Microsoft official web-site. This update eliminates potential problems with incorrect detection of the number of cores in triple-core CPUs, but it is not mandatory. Even without it our Windows Vista Ultimate testbed could see all three cores just fine.
Keeping in mind that Phenom X3 is actually not that much different from Phenom X4, the most interesting thing about it is the price. After a lot of hesitation, AMD decided to set the following official prices:
- AMD Phenom X3 8750 (2.4GHz) – $195;
- AMD Phenom X3 8650 (2.3GHz) – $165;
- AMD Phenom X3 8450 (2.1GHz) – $145.
So, triple-core Phenom X3 family is positioned as something in-between quad-core Phenom X4 and dual-core Athlon 64 X2. As a result, the new processors fit logically into AMD’s product map and become competitors to Wolfdale family of dual-core Intel Core 2 Duo processors, which prices were reduced this past Monday.
But will three cores of the new Phenom X3 be able to compete successfully against two Wolfdale cores? Our test session will try to answer this question. But before we move on to the results, let’s take a closer look at the triple-core processor sample we got into our lab this time.
