First Tests: AMD’s Phenom CPU won’t scare Intel

CPU
AMD’s new Phenom processors and Spider platform for desktop systems incorporate some impressive steps forward for the chip maker. The chips, which are made using a 65-nanometre manufacturing process, feature both a native quad-core design and enhanced power-management technology. But when we ran a Phenom- and Spider-based computer through our lab, the results revealed that AMD still has a lot of work to do.

Problems already?
AMD sent unlocked versions of its 2.6GHz Phenom 9900 chip to reviewers, but AMD has now pushed back the release of this chip, and the 2.4GHz 9700, to the second quarter of this year. The 9900 is slated to retail for less than $500 and the 9700 should be under $400. Until then, the fastest Phenom chips that you’ll be able to find are the 2.2GHz Phenom 9500 ($360 street price at the time of writing) and the 2.3GHz Phenom 9600 ($420 street price). An unlocked, overclockable Black Edition 2.3GHz Phenom should also be available by the time you read this.

Though both the 9500 and the 9600 appear to be widely available now, AMD recently owned up to a bug in the first generation of its Phenom and Barcelona chips that can cause systems to lock up when running certain rare software workloads at clock speeds greater than 2.4GHz. A BIOS upgrade is available as a workaround, but according to enthusiast website The Tech Report, the workaround slows performance by up to 10%. The faster Phenom processors should have this error corrected.

Discouraging results
Now that we have a Phenom CPU in our labs, we can make better comparisons with test systems built around Intel-based processors (see the chart “Penryn vs. Phenom: two different worlds” on page 32). Our Phenom test setup used the same supporting components – an nVidia GeForce 8800GTS-based graphics board with 320MB of RAM, two Western Digital WD2500AAJS hard drives in a striped RAID array, and 2GB of DDR2800 RAM – as our earlier Penryn tests did. We tested our unlocked Phenom at both 2.6GHz and 2.3GHz on an Asus M3A32-MVP Deluxe motherboard with an AMD 790FX chip set.

When running the Phenom 9900 at 2.6GHz, our test system posted a score of 107 on WorldBench 6 Beta 2, not all that much faster than the average mark of 96 turned in by the systems we’ve seen based on the last-generation Intel Core 2 Duo E6600 CPU. The E6600, an older chip, goes for around $320, compared with the projected $500 price for the 9900.

Of course, the fastest Phenom chip out now is a 2.3GHz model, and at that speed our test PC’s score dropped to 99 – not much of an advantage at all for a CPU that costs about $100 more than its aging competition. And there’s no comparison to the ultra-high-end Penryn chip we evaluated on the same test bed: that $1700 CPU clocked in at a WorldBench 6 Beta 2 score of 127. By the time AMD’s faster Phenom processors are ready to ship, Intel will likely have mainstream Penryn chips ready to compete.
The first Phenom-based PC we could test – featuring a 2.3GHz Phenom 9600 and an ATI Radeon HD 3870 graphics card – didn’t fare much better with its score of 95.

AMD currently has no answer to Intel’s SSE4 instructions for accelerating specific multimedia operations, which may widen the performance gap further in selected applications. On the other hand, unlike Intel’s quad-core models, which are basically two dual-core CPUs using a shared bus interface, Phenom has four distinct cores, which should offer benefits. The performance comparison may evolve as more applications begin taking advantage of multimedia instructions such as SSE and leveraging more than two CPU cores, but given the size of Intel’s head start, it’s unlikely that AMD will be able to truly close the gap.

At AMD’s Phenom launch event in November, we also tested a 2.6GHz Phenom 9900-based system featuring two of ATI’s recently released Radeon HD 3850 graphics cards, an MSI motherboard using AMD’s 790FX chip set, and 2GB of DDR21066 RAM. On WorldBench 6 Beta 2, AMD’s test system received a score of 105, significantly faster than the 93 posted by a previously tested system with AMD’s last-generation 3GHz Athlon 64 X2 6000+, though not nearly the 32% gain that AMD touts. While representing an impressive boost over AMD’s previous CPUs, it’s nowhere near enough to make Intel sweat.

Tough times
All things considered, 2007 probably hasn’t been AMD’s favourite year. In fact, things haven’t been sunshine and roses for the company since the middle of 2006, when Intel introduced its Core 2 Duo CPUs. After three years as the performance champ, AMD was suddenly getting its clock cleaned, so to speak: when running at the same clock speed, Core 2 Duo chips were anywhere from 10 to nearly 20% faster than comparable Athlon 64 X2 processors.

Not only that, but almost immediately after AMD’s US$5.4 billion acquisition of GPU and chip set vendor ATI, that company slid well back in its own performance race with nVidia. The acquisition gave AMD expertise in GPUs and chip sets, plus independence from nVidia – a longtime ally that had started supporting Intel the year before – but it added to the perception of AMD as firmly occupying second place. Losing money for several straight quarters hasn’t helped, either.

In 2007 AMD also fell increasingly behind in the competition for better process technology. Intel manufactures its Penryn chips using a 45-nanometre process, which allows the company to pack in more transistors per square millimetre than in the 65nm process AMD is introducing with its Phenom chips. That can translate to more chips per slab of silicon for cheaper production, giving Intel yet another advantage.

AMD’s latest 65nm Opterons, with their parsimonious power usage, are competing well in the server market, but that does nothing for mainstream users.



Platform news
With no way to regain the CPU performance crown, AMD has tried to focus the media’s attention on its graphics board and chip set technologies. This isn’t all misdirection, though, since performance in games often relies more heavily on a system’s GPU than its CPU.

The new Spider 790FX chip set plays right into that with support for AMD’s HyperTransport 3.0 I/O bus, which has 20% more bandwidth than its predecessor. The 790FX can also combine four ATI 3800 PCIe 2.0 graphics cards on one motherboard – a technology that AMD calls CrossFireX. Preliminary tests on such sites as Anandtech indicate that these 3800-series graphics cards match up well with all but nVidia’s fastest models in performance, and that they have very good power-consumption numbers.
Speaking of power consumption, AMD is offering users the ability to tweak consumption (as well as the speed of Phenom chips) to a startling degree, using a new utility called OverDrive.

No mere overclocking utility, OverDrive lets users adjust voltage settings and clock multipliers on a per-core basis. For example, if you have a game that takes advantage of only two CPU cores, you can build an OverDrive profile that overclocks two of the Phenom’s four cores and ratchets down the speed on the other two, conserving power and lowering heat to create more headroom for the two cores that you’ll be using heavily.

If you would prefer not to tweak every bit of your hardware manually, OverDrive includes a one-click performance tuning option that benchmarks your system and ratchets up speeds to a safe level automatically.

If AMD’s 65nm manufacturing process manages to produce Phenoms with overclocking headroom, gamers could find value in the unlocked, 2.3GHz Black Edition Phenom chip.

According to AMD, motherboards based on its 790FX chip set should be inexpensive in comparison with the latest motherboards built for Intel’s Penryn processors. Consequently Spider-based systems could present an interesting choice for mainstream gamers – that is, you could well spend less on the CPU, motherboard, and memory, yet combine them with up to four fast but reasonably priced 3800-series graphics boards. Although the CPU will not be able to compete with similarly priced offerings from Intel – especially with the mainstream Penryn processors expected to launch early in the year – a quad-CrossFire system could be an affordable gaming powerhouse.