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First look: AMD's Athlon MP 1800+ processor

A first look at AMD's new multiprocessor chips
— 1:55 AM on October 15, 2001

AMD IS LAUNCHING A SERIES of new Athlon MP processors today, finally bringing the Athlon MP up to the same clock speeds the non-multiprocessor Athlons have enjoyed for a while now. Normally, upon such an event, we here at TR would have a massive benchmark-fest ready for you, packed with results from all the competitive hardware in a wide range of tests—all thanks to the magic of our child-labor benchmarking sweatshop in Malaysia.

This is not that article. Instead, we're going to give you a quick first look at AMD's new high-end multiprocessor chip, the Athlon MP 1800+. We'll follow up with a more comprehensive article later, once our sweatshop delivers more results. Nevertheless, we've done enough preliminary testing to give you some idea how the new Athlon MP 1800+ compares to its predecessor, the 1.2GHz Athlon MP. Also, we've got the dirt on all the new developments in the AMD SMP scene.

Athlon XP, Athlon MP — it all makes sense now
The first thing you need to know about the new Athlon MP chips is that they're nearly identical to the new Athlon XP processors, both inside and out. If you haven't already read our Athlon XP review, go do so now. It'll bring you up to speed on the Athlon "Palomino" core and the rest of the Athlon XP news. Note that all Athlon MP processors, including the older 1GHz and 1.2GHz versions, are based on the Palomino core. Palomino is just now making it into the mainstream desktop market as the Athlon XP.

To review, the new Athlon MP shares a number of things with the Athlon XP: its core architecture, its new organic packaging, and its funky new "model number" naming scheme. So the Athlon MP 1800+ doesn't actually run at 1.8GHz. Instead, it's a 1.53GHz chip that AMD has endowed with a new name to signify its performance. Like the Pentium 4, Intel's new Xeon chips (which are basically Pentium 4s that fit into a different socket) run at high clock speeds, but don't execute as many instructions per clock as AMD's Athlon chips. The model numbers are a marketing device, and they're probably a necessary evil.

I should note, though, that AMD's "model number" marketing scheme makes more sense in the desktop market, where they have to sell to consumers, than it does in the markets where the Athlon MP is likely to sell: the markets for workstations and servers. Certainly the more savvy folks buying such high-end systems can understand the disjunction between processor clock speeds and actual performance. However, in efforts such as this marketing scheme of AMD's, consistency is important. I suppose using the model numbers for the SMP parts makes sense, even if it does seem less appropriate here.

Whatever you think about that, the new Athlon MP models are coming. The lineup, with initial prices, will look like so:

  • Athlon MP 1800+ (runs at 1.53GHz) — $302
  • Athlon MP 1600+ (runs at 1.4GHz) — $210
  • Athlon MP 1500+ (runs at 1.33GHz) — $180
  • 1.2GHz Athlon MP — $175
  • 1GHz Athlon MP — $165
Unlike the desktop processors, the Athlon MP line will not have a 1700+ (1.47GHz) model. Qualifying an additional speed grade for use in SMP systems probably wasn't worth the extra effort to AMD. (Intel recently made a vaguely similar move, releasing a 2GHz Xeon, but only qualifying the chip for use in workstations—not in servers.)

With these prices, AMD is charging a premium of exactly $50 over the Athlon XP for these multiprocessor chips. By comparison, Pentium 4 chips at 1.7GHz are selling for about $180, while the 1.7GHz Xeon costs about $300.

AMD dually school
For the uninitiated, let's talk for a second about what makes SMP so great. In this context, we're talking about "symmetric multiprocessing" of the dual-processor variety, although very high-end servers may run four, eight, sixteen, or even more processors at once. What we're concerned about is the realm of mere mortals, where x86-compatible chips can pair up to power workstations or mid-range servers.

For such systems, dual-processor setups are great. They're not the end-all, be-all, however. A dual-processor computer is rarely outright "twice as fast" as a single-processor box. Multiprocessor systems don't deliver linear performance increases as the number of processors in a system grows. There are too many bottlenecks, from shared hardware resources to un-optimized software apps, to allow a second processor to double the speed of a system.

AMD SMP is especially sweet, though, because AMD has tackled one of the most important potential bottlenecks in a system: the front-side bus. This bus is how a processor talks to the rest of the system. Most multiprocessor systems (including Pentium IIIs and Xeons) require the processors in a dual-CPU setup to share a single front-side bus, but AMD's 760MP chipset is different. Rather than host both processors on a single FSB, the 760MP sports two, separate 266MHz front-side busses. The connection between the system and each processor is dedicated, or point-to-point.

This bus configuration is unique in the x86-compatible SMP world, and at least theoretically, it should allow Athlon MP systems to squeeze more performance out of that second processor than could many systems. Add to that all the other reasons duallies are so sweet—primarily, they avoid slowing down when a single CPU-killer task decides to hog the processor—and you've got a recipe for excellence.