Review: AMD's Latest Tri-Core Phenom


About one month ago, Sunnyvale, Calif. based Advanced Micro Devices released their 50 series of the Quad Core Phenom CPU. With this series, they fixed a bug, known as the TLB erratum, which was present on the previous 00 series.

On Tuesday, April 23, AMD launched their latest Phenom, the X3 series. The X3 is built on the same silicon as the X4, except it is a triple core processor. The Test Center evaluated the Phenom X3 8750 and found it to function just as we expected.

To get an accurate baseline, we installed the 2.4 GHz 8750 into the same testbed that we tested previous AMD processors. This is an Antec case housing a Gigabyte GA-MA78GM-S2H, with 2 GB RAM, an Ultra 3X 1000 watt power supply, a 160Gb SATA HDD, and running Windows Vista Ultimate with SP1.

There has been speculation throughout the Internet theorizing that the X3 is really a quad core X4 with one of its cores disabled (either by design or due to a bad core found during QA).

Here's the deal:

An AMD spokesman confirmed that it is indeed a quad-core die with one of the cores turned off, but it is not done strictly to salvage quads not up to snuff (although that does happen too). AMD polled their OEM customers early in the design stage to see if there was a potential market for the triple core; the overall response was positive.

Since each core in the X4 has its own clock, they can be tested individually during QA. This gives AMD a few options. If one of the cores is slower than the other three, the CPU can be configured as a quad core at the slower frequency, or a triple core at the faster speed. The decision can be made based on which there is more of a demand for at that particular moment. In addition, should one of the X4 cores fail the QA process altogether, the processor can still be converted into a fully functional X3.

As mentioned earlier, AMD's goal is to help builders create entry-level, sub-$500, performance PCs that can do a lot more than a dual core PC for the same or even less cost of acquisition. (As a side note, we were informed that since the Xbox 360's configuration includes a similar three core setup, gamers should be interested in seeing how the X3's triple core set up plays out in the future as more and more games are authored for Microsoft's console and then cross over to the PC.)

As anticipated, the three core 8750's results fall somewhat short of the quad core unit, but ahead of the dual core. Using Primate Labs benchmarking tool Geekbench 2, the X3 8750 scored a respectable 3461. Our tests of the 2.5 GHz X4 9850 in the same motherboard yielded a 4333 and the 2.5 GHz dual-core 4850e attained a 2619. Considering the 8750 is 100 MHz slower than the other two chips, its score is about where we predicted it would be.

The X3 CPUs are rated with a maximum TDP of 95 watts, compared to the X4's maximum of 125 watts. AMD is positioning the new processors as part of their "Cartwheel" platform which also includes motherboards designed around the inexpensive 780G chipset. Cartwheel is AMD's vision of how to enable more powerful, main-stream PCs. The idea behind Cartwheel is that you can build a more robust computer, with strong integrated graphics, at a lower cost. AMD claims that historically integrated graphics has made up approximately 90 percent or more of desktop and laptop retail sales in North America, and they are using Cartwheel to target that market.

With prices ranging from $145 each per thousand units (for the 2.1 GHz 8450) up to $195 each per thousand for the 8750, AMD is hoping that builders and customers will take advantage of getting "an extra core" for free, citing that the only current Intel offerings under $200 are dual cores. Since it is socket compatible with most AM/AM2 boards, the X3 series is also a relatively inexpensive upgrade option for customers looking to enter the multi core arena.