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Intel's Pentium M 760 versus AMD's Turion 64 ML-44

Mobile Goliath meets would-be David

ALTHOUGH INTEL HAS BEEN STRUGGLING on the desktop front of late, things on the mobile side have been going just fine, thank you. In fact, the Pentium M has been doing so well that Intel's desktop line will eventually be migrating to a processor based on a similar architecture. Heck, even Apple joined in on the fun. Near the top of the heap is the Pentium M 760, which features a 533MHz front-side bus, an operating frequency of 2.0GHz and a whopping 2MB of L2 cache.

AMD's answer to the Pentium M is the Turion 64, an Athlon 64-based design which rides in a 754-pin socket. The Turion 64's attributes include an on-die memory controller, a 1GHz HyperTransport link, and of course the ability to run 64-bit code. The model we'll be looking at today is the ML-44, a new chip with a 2.4GHz operating frequency and 1MB of L2 cache.

We have been watching the mobile processor space for a while now with some interest, wondering whether the Turion 64 really matches up well against the Pentium M. The Pentium M's power-saving features and performance per watt are the stuff of modern legend. AMD has done well with Opteron in servers and the Athlon 64 in desktops, but surely AMD's K8-derived mobile competitor doesn't match up with the likes of the Pentium M. Does it?

Well, we wanted to find out before the game changes again. Intel's recently announced Core Duo marks the beginning of a transition to multicore processors in the mobile space, and AMD has stated its intention to make a dual-core version of the Turion, as well. Core Duo laptops are just starting to arrive on the market, although volumes are still somewhat limited. With that in mind, let's take a quick look at the two most widely available mobile processors today: the Pentium M versus the Turion 64.

The combatants
We'll start off with an up-close and personal view of the two contenders:

The Turion 64 ML-44 (left) and Pentium M 760 (right)

Being mobile chips, neither the Pentium M 760 nor the Turion ML-44 has the protective "heatspreader" cap that's become standard on desktop processors. Instead these processors look more like an Athlon XP or an old-school Pentium III.

The Turion 64 ML-44
The ML-44 is the latest addition to AMD's Turion line of mobile processors. On the surface, the Turion has much in common with Socket 754 Athlon 64 chips. It has an on-die memory controller capable of addressing a single channel of DDR400 memory, as well as the ability to run 64-bit code—not even the new Core Duo can do that. Depending on model, the Turion features either 512KB or 1MB of L2 cache. Turions also feature support for the NX bit, which can help prevent malicious exploits based on buffer overflows.

Being a mobile line, low power consumption is a key feature of the Turion 64. All Turions support AMD's PowerNow! technology, which dynamically scales clock speed and voltage over a wide range in response to CPU loads. Additionally, although Turion 64s bear more than a passing resemblance to the Socket 754 Athlon 64, the Turion can operate at significantly lower voltages relative to desktop chips, which cuts down significantly on power consumption.

Finally, AMD has segmented the Turion 64 into two model lines, one focusing on performance, the other on battery life. This product segmentation shows itself in the TDP—or thermal dissipation rating—of the two lines: The ML line of Turions has a TDP of 35W, while the MT line has a TDP of 25W.

The ML-44 we're testing today is AMD's fastest model, featuring 1MB of L2 cache and a maximum operating frequency of 2.4GHz. With PowerNow! enabled, the system will scale the processor's operating frequency from 2.4GHz all the way down to 800MHz depending on CPU load. The voltage scales from 1.0V at 800MHz to 1.35V at 2.4GHz.

The motherboard we're using for Turion 64 testing is MSI's RS482M-IL. This microATX motherboard is based on ATI's Radeon Xpress 200M mobile chipset, and its integrated graphics should be similar to those on a Turion 64 laptop with the same chipset.

The Pentium M 760
The Pentium M 760 is at the upper end of Intel's mobile line, and is an example of how the Pentium M has evolved over time. While the first Pentium M processors had 1MB of L2 cache and ran on a 400MHz bus, newer examples such as the 760 have a giant 2MB of L2 and a 533MHz front-side bus. Finally, like the Turion 64, the newer Pentium M chips add support for the NX bit.

In addition to these changes, memory bandwidth has improved considerably over time thanks to newer chipsets. The first chipsets could only address a single channel of DDR333, putting the Pentium M at a disadvantage relative to the competition. The newer 915 chipset we're looking at today, however, can address dual channel DDR2 at 533MHz, a huge increase in memory bandwidth. While some of this bandwidth will likely go untapped thanks to the relatively slow 533MHz front-side bus, it's better to have an excess of memory bandwidth, especially when using on-board graphics with shared memory.

The Pentium M 760 has a maximum operating frequency of 2.0GHz. Using Intel's SpeedStep technology, the system will dynamically clock the processor anywhere from 800MHz up to the maximum 2.0GHz. The voltage scales from 0.714V at 800MHz to 1.315V at 2.0GHz.

Unlike the Turion 64, the Pentium M can't run 64-bit code. Given that most laptops can't accept more than 4GB of memory, that limitation may not be much of an issue for the Pentium M. 64-bit computing does have tangible benefits in certain scenarios, but those arguably won't matter for mobile computing for some time yet.

For our tests, the Pentium M 760 will be sitting in an AOpen motherboard, the i915Ga-HFS. This ATX board features the Intel 915GM mobile chipset. Like the MSI board for the Turion, it should give us a reasonable approximation of a laptop based on the same chipset, in terms of both power consumption and graphics power. Not only that, but both this Pentium M mobo and our Turion 64 motherboard are strong candidates for use in quiet computing applications like home theater PCs, as well.

The match-up
Ours is not a perfect world, and we acknowledge that this is not a perfect match-up, at least not in terms of price. The problem is that AMD's Turion ML-44, priced at $354 by AMD, lands in the middle of a large gulf in Pentium M pricing. Our two closest options for comparison were the Pentium M 760 at 2.0GHz, with a price of $294, and the Pentium M 770 at 2.13GHz and a price of $423. The $60 price difference between the 760 and the ML-44 was slightly less than that the $69 separating the 770 from the ML-44, so we based our comparison on the former.