CPU AMD Phenom X3 8750 (Toliman)

These days, the increase of the CPU speeds is achieved in a number of ways. The traditional way is raising the clock speeds. Normally, CPU manufacturers gradually raise the clock speeds within the same process technology (if the process offers some margin for clock speeds). Then they produce CPUs of new steppings whose clock speed capabilities are somehow higher due to so improvements to the process technology. Once every two or three years, manufacturers switch to a finer process technology, which in the end allows starting the cycle all over again and then raising the clock speeds more times.

The second way implies a radical change to the CPU architecture. This way is quite rarely used by the manufacturers (once every few years) and as a rule the new architecture results in a dramatical rise of the performance. A typical example is the transition of Intel's processors from the NetBurst architecture to the Core architecture.

The third way is extensive which implies an increase in the number of cores within one CPU. By its significance, this approach is not so efficient unlike the previous two (in the desktop computers). The problem is that a vast majority of current software is not optimized for multithreading. In these cases, we deal with the situation when the quad-core CPU loses at speed to the single-core CPU but running at a higher clock speed. However, today's domination of dual-core processors is easy to explain - manufacturers have ceased to produce single-core processors. From the viewpoint of the common user, the situation is quite simple: the user gets the second core "free of charge", but at the same time such a CPU allows making the experience of a multithreaded operating system more comfortable. As regards the "nonconventional" users, it's just this category that gains the most advantage from multi-core processors. Normally, these are engineers, designers, artists, video editors, and programmers who use dedicated software suites. We are not taking this user category into account. The thing is, the cost of professional software is often much higher that cost of the hardware, so the costs for the latter do not count. On these workstations, they use top-end CPUs with the maximum number of cores and the highest clock speeds. That is understandable - the faster the workstation is, the more volume of work it performs, thus more money is earned.

Now let's look at AMD's position as of early 2008. The situation was hard indeed - although the company successfully migrated to the 65-nm process technology, it did not let the company overcome the 3 GHz bar. The 3000 MHz still remains the maximum for the Athlon X2 (model 6000+) only. Processors of this series consistently lose at speed to Core 2 Duo processors, and the only way to sell them is to push down the price. The situation with the К10 architecture on which Phenom processors are based was even worse - the maximum clock speed did not exceed 2.4 GHz (the model X4 9700). Moreover, Phenom X4 processors were priced high but lost at speed to Intel's quad-cores. In the end, AMD found itself in a stalemate - no way (or really difficult) to raise the clock speeds, and the transition to the 45-nm process technology is continuously postponed (Intel migrated to this process late in 2007), and the change of the K10 architecture now is out of the question.

The situation was compounded by the hype around the notorious "TLB error" which in theory might result in a system crack. For the regular user, an error like that is not critical because of the low probability and low damage rate (no problem if you have to re-play a mission in a game). For the professional user, the "TLB error" was like giving up use of K10 architecture processors. The probability of emergence of the error situation is also low, but the probable damage is dramatically higher. Needless to say, AMD did its best to calm down the users. In particular, a patch (enabled/disabled from the BIOS) was released, which vividly resulted in a drop of performance by 10% on the average (in some applications - to 25%).

Clearly, ways out of that situation had to be found. The first move by AMD in 2008 was the release of Phenom processors of the new stepping (B3), in which the TLB error was fixed on the hardware level. Using this stepping, AMD is announcing a new line of it хх5х processors: 9550, 9650, 9750, and 9850 Black Edition, where the "5" definitely points to a new stepping. Besides, the B3 stepping allowed to raise the clock speed a bit - to 2.5 GHz (the model X4 9850). On top of that, AMD revised its pricing policies, so almost all of the CPU models were made attractively priced.

All that is fine, but AMD should have done that originally, on the moment of announcing Phenom processors. But what AMD did further is unprecedented in the IT industry - these guys are releasing the 3-core Phenom! The idea proved simple like all the works of genius - there was a need to create a processor which could struggle Core 2 Duo in the regular applications and beat C2D in multithreaded applications due the "redundant" core. Clearly, the price for such a CPU should be attractive enough to make the buyer think of purchasing a 3-core product by AMD.

So, here it is - CPU AMD Phenom X3 8750 (Toliman) based on the Agena core. The reduction in the number of cores was effected in the industrial conditions, and the source chips are both partly rejected Agena cores and the fully operative ones (depending on the rate the process technology is polished). However, the user has no reasons to be pleased. There is no software or hardware facility to activate the fourth core. Apart from reduction in the number of cores, engineers at AMD have not done any other cutbacks. In particular, the size of the L3 cache is 2 MB as it is in the Agena. Each core has 128K L1 cache, 64 K of which is allocated for data and the second part - for instructions. Then, each core is equipped with L2 cache 512 K. In the end, the Toliman core has absolutely the same area as the Agena (285 sq. mm) and the same number of transistors (450 mln). The set of supported technologies (С1E, Cool & Quiet) and additional instructions has remained unchanged, starting with MMX, 3DNow! up to SSE4A, x86-64. Finally, the Toliman core offers the same integrated memory controller as is in the Agena with support for 16 GB of DDR2-800/1066 memory.

However, the Toliman and Agena cores have some functional differences. To start with, CPU Phenom 3X run on the HyperTransport bus at 1.8 GHz, whereas some top-end quad-core CPU operate on the 2 GHz bus. The same can be said about the heat emission - for all the 3-core AMD processors, the maximum TDP is 95W, and 125 W for the top-end quad-core processors. However, powerful modern motherboards are equipped with overclocking tools and are able adjusting the HT multiplier. So, the advanced user can bring some settings of the Phenom 3X to those for Phenom 4X (the number of active cores, of course).

We'll talk about the overclocking later, but now let's look at the CPU itself.

And the information displayed by the CPU-Z utility:

As you can see, AMD Phenom X3 8750 offers the reference HTT speed 200 MHz and the multiplier set to 12. Therefore, the resultant clock speed of the CPU is 2.4 GHz and to date this model is one of the fastest of all in the line of 3-core processors. Besides the 8750 model, AMD has released a few more processors of lower clock speeds. For a convenient perception, we summed them all up in a table ("diluted" with quad-cores).

Overclocking

A few words on the overclocking. On the one hand, overclocking the AMD Phenom processors basically makes no difference from overclocking of any other processor. We've got a CPU with the fixed multiplier and the reference HTT bus whose raise of frequency results in a raise of the clock speed. Certainly, with overclocking like that we must keep an eye on the RAM frequency which is set with one of the multipliers and rises proportionally to the rise of the HTT. For now, the overclocking process looks like overclocking the Intel platform where the memory frequency rises following the FSB.

However, we should keep it in mind that overclocking results in the rise of the HyperTransport bus frequency, although the feature for adjustment of the multiplier (available on most motherboards) allows to keep this parameter within the operating range. So, overclocking to this point is similar to overclocking AMD Athlon (X2) processors. But there is one fine point - in the processors of the K10 architecture the frequency of the memory controller also rises following the HTT. And, starting from a certain HTT speed, the CPU won't run stably because the memory controller is unable to operate at a frequency which is too high for its operating range. However, there is still a margin for the clock speed in the CPU. In this case, the feature for the multiplier adjustment comes in handy, which is responsible for the operation of the memory controller. Unfortunately, this feature is not available in some motherboards, but if its the advanced user can squeeze out the most of the Phenom CPU.

To keep track of the numerous parameters, you can make use of the AMD OverDrive utility which looks like this:

AMD OverDrive utility (click to enlarge).

As you can see, we reduced the HyperTransport bus speed to 7, so the nominal blocks of the CPU run in almost the nominal mode.

AMD OverDrive is quite a powerful and convenient program. Its merits are about the information block which provides all the available data on the CPU, memory, chipset, and the video card. The thing is, no one else but the engineers at AMD knows the technical traits of the Athlon and Phenom processors, chipsets of the 7th series and Radeon graphic cores better. However, in terms of overclocking, the AMD OverDrive utility is definitely weak - even in the "advanced" mode the adjustment ranges are too small.

Therefore, in view of the above traits, we verified the overclocking capability of the test CPU.

In the end, we attained a stable operation at ~3.12 GHz with the voltage Vcore = 1.4V (nominal = 1.2 V). We are still not making conclusions regarding the result - more statistics has to be collected. In our forthcoming materials, we will come back to the matter of overclocking Phenom processors and compare them versus the mode of overclocking Intel processors. Besides, Phenom processors have some very interesting points, one of them is about quite an unusual setting of the multiplier at a very small increment (below 0.5).

Performance tests

In our test setup, we used the following hardware:

Results for synthetic benchmarks

Tests of application software

Video encoding (DivX, Xvid) was measured in seconds, i.e. the less the better.

Data compression (WinRAR) was measured in K/sec, i.e. the more, the better.

Tests with Games

Final Words

On the moment of running the tests (mid-October 2008), the retail prices for Phenom X3 8750 start with $172. In our humble opinion, that is a bit too expensive and will not let AMD to overcome the trend of user migration to Core 2 Duo. Dual-core Intel processors for home-based computers are the major competitors to the Phenom X3 product line. We say that with confidence because the few professional users are very well aware of what software they work on, how this software is optimized for multithreaded processing, and on which platform (Intel or AMD) this software runs faster. Therefore, these users purchase various quad-core processors regardless of the prices (although some quad-core CPUs are currently priced below $200!).

Besides, in the struggle for a place in the home-based PC the Phenom X3 product line has one more competitor. That is AMD Athlon X2 @ 3 GHz (Athlon X2 6000+) whose price in the Moscow retail starts with $120. It offers only two cores, but that is quite enough for most home-based applications not optimized for multithreaded processing (primarily, games). At the same time, the saved money can be spent on a more powerful video card. We'll know how this statement is true in our forthcoming review once we compare the performance of Athlon X2 6000+ versus the other models of the Phenom X3 product line (8650, 8550, and 8450). For now, we can only state that in terms of performance the model AMD Phenom X3 8750 is able competing on par with lower and middle models of the Intel Core 2 Duo line. But we can safely recommend this processor for purchasing, and its retail price should be much lower.