New AMD CPUs: Midrange Speed, Low Power Draw

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AMD's latest Phenom CPUs are fast, but not the fastest chips around. That distinction falls to Intel's Core series of CPUs, which are 5 to 10 percent speedier, clock cycle for clock cycle. Still, the new units--the Phenom X4 9950 Black Edition, the Phenom X4 9350e, and the Phenom X4 9150e processors--cost less than Intel's most recent chips.

The high-end Phenom X4 9950 Black Edition (CPU only) compares well, price-wise, with Intel's quad-cores, especially the newer 45-nanometer-process Q9550, Q9450, and Q9300. For example, the Q9550 costs about $550, whereas the Phenom X4 9950, which uses a 65-nanometer process, costs about $235.

Performance-wise, though, it's more comparable to Intel's 65-nm Core 2 Quad Q6600 and Core 2 Quad Q6700. The 65-nm Phenom X4 9950 provides a 4 percent speed increase (2.6 GHz, up from 2.5 GHz) over the previous flagship product, the 9850. The Black Edition CPUs, like Intel's Extreme models, allow you to increase the clock multiplier. Most CPUs are locked at a fixed multiple of the frontside bus--for instance, 12X with a 200-MHz bus, or 2.4 GHz. The Phenom X4 9850 will now be available only in a cheaper, locked version.

All three new AMD chips use what the company refers to as B3 silicon, with a slight revision of AMD's original Opteron/Phenom design that eliminates a potential problem that reportedly could lock the CPU under a heavy virtualization load. AMD claims there were no reports of the problem ever occurring in a desktop PC; but as soon as the problem was reported, motherboard vendors implemented an optional BIOS fix at AMD's behest. (See "First Tests: AMD's Phenom CPU Won't Scare Intel" for additional information on the bug.)

A Green CPU?

AMD may have found a nice space for itself in the mainstream with its new low-power-consumption, 65-watt TDP (Thermal Design Power) quad-core Phenom X4 9350e and Phenom X4 9150e. The 9150e is slightly slower and cheaper than the 9350e--1.8 GHz to 2.0 GHz, and $175 to $195.

Intel's Core 2 Duo CPUs are also rated at 65 watts TDP, but its quad-cores are rated at 95 watts and 105 watts. However, Intel's quad-core processors also run at clock speeds significantly higher than AMD's 9350e and 9150e do, so the difference in performance per watt probably isn't as significant as it might seem.

We put the Phenom X4 9950 and 9350e through their paces with a recently completed beta version of WorldBench 6 that tests power consumption as well as real-world performance. On a test bed with 2GB of 1066-MHz DDR2 memory, an nVidia 8800GTS graphics board, an Asus M3A32-MVP Deluxe motherboard, and two 250GB Western Digital WD2500AAJS hard drives in a striped RAID 0 configuration, the Phenom X4 9950 turned in a score of 104. That compares well with the mark of 108 for Gateway's GM5632E and the score of 97 for Commodore Gaming's CGX, both of which used Intel's 2.4-GHz Q6600.

On the other hand, it fell well short of the average of 118.5 scored by the six PCs we've tested that use the 2.66-GHz Intel Q6700. The test PC with the 9950 also ran more slowly than the Dell XPS 420 we tested with a 2.83-GHz Intel Core 2 Quad Q9550; that system earned a WorldBench 6 score of 122.

For the low-power 9350e test bed, we used 2GB of 800-MHz DDR2 memory and the same striped array, with a much less expensive Gigabyte GA-MA78GM-S2H motherboard. Though the Gigabyte board features integrated ATI HD3200 graphics, it also has a PCI Express x16 slot, so we used the same nVidia 8800GTS discrete graphics board for a better comparison between the two AMD CPUs. For a 2-GHz system, the Phenom X4 9350e's WorldBench 6 score of 87 was quite good.

The Phenom CPUs' power numbers fell largely as expected. The 9950 setup drew 227 watts under load over a 5-minute span, 3 watts while off, 7 watts in sleep mode, and 209 watts when fully awake but idle. Meanwhile, the 9350e setup drew only 162 watts under load, 1.6 watts when off, 3 watts asleep, and 147 watts at idle.

We used a rather beefy, 750-watt Corsair TX750W power supply for both setups, which exceeded the 9350e's requirements by a large margin. You should see lower power numbers for that setup with a lower-wattage power supply.

If you use programs that take advantage of multiple processor cores, or if you often run many apps at once, you can buy four cores and gulp less juice with AMD's new e-series Phenoms.

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