Since AMD first announced its 760MP and newer 760MPX chipsets, the buzz about dual-processor AMD systems has grown steadily louder. The reasons are clear -- AMD processors are priced below their Intel competitors, and the high-end workstation and small server markets have been fed a monotonous diet of Pentium-family solutions, priced for healthy Intel profit margins, for a long time.

System cost has always been the overriding factor restricting dual-CPU systems to the workstation and server segments instead of the mass market. The i860/Xeon Pentium 4 combination is certainly powerful, but can be awfully expensive -- at least for Intel's steep Xeon prices, if not so much for its use of RDRAM instead of the formerly much cheaper DDR.

Saying that the AMD label guarantees lower prices, however, is simplistic. The company seems to have taken at least one page from Intel's book in that only Athlon MP processors are certified for multiprocessing use, although there's no physical difference between the Palomino-cored Athlon XP and MP. (Indeed, AMD was talking about offering a Duron MP not long ago, but the market has yet to voice any measurable demand for one.)

The main difference is that AMD subjects Athlon MP chips to more rigorous multiprocessing tests; the lack of similar certification doesn't necessarily mean that Athlon XP or Duron CPUs won't work in a dual-processor configuration, but that it would entail more risk than the price savings would warrant.

The extra testing translates into slightly higher price for the Athlon MP versions, so at the speeds AMD currently has available (topping out at 1.6GHz for the Athlon MP 1900+), the Pentium 4 Xeon is a bit more costly, but competitive. Once you reach the 2.0GHz or 2.2GHz P4 Xeon level, by contrast, all hell breaks loose, but that's standard pricing procedure for Intel.

Double the Value

Real differences, however, become apparent in motherboard cost. Even one of the higher-end ASUS A7M266-D 760MPX boards will only run you a bit over $200, and Tyan's Tiger 760MP is even cheaper. Most bare-bones Pentium 4 Xeon motherboards cost $400 to $500, with deluxe models reaching well over $800. Even for premium-priced workstations, this can add a lot to the bottom line, and makes the P4 Xeon mostly a nonstarter for performance-hungry buyers who are tempted to try a dual-CPU desktop. On the other hand, basic 760MPX system costs are close to those of high-end uniprocessing platforms.

Software also plays a part, but with Windows NT, 2000, and XP Professional all offering symmetric multiprocessing (SMP) support, the groundwork has definitely been set. Specific SMP application support is still a little sparse, aside from a few high-end graphics and entertainment programs, but dual processing has inherent advantages even at the operating system level. Overall, you can expect no worse than single-CPU performance at the application level, with the potential for nearly doubled speed for SMP-aware programs, plus enhanced stability and multithreading at the OS level.

The 760MPX's price/performance may be hard to resist for cash-strapped firms seeking to save on server or workstation costs, as well as PC enthusiasts craving more desktop power at only a slightly higher price -- and maybe even a new mass market of high-end, dual-processor desktops. There have been some attempts at this before, most recently with the VIA Apollo Pro133T, but there are notable differences this time out.

The VIA chipset came to market much too late, offering a dual Pentium III setup when all eyes had turned to the Pentium 4 and Athlon; the AMD 760MPX is positioned far better, as the Athlon XP/MP are viewed by many enthusiasts as the top-performing x86 processors. And when current Athlon MP prices are compared to historical Pentium III levels, AMD wins that battle as well.

Oops, USB

If there's one potential roadblock confronting the 760MPX, it's product availability. With all of the press and anticipation about the chipset, we certainly expected a few more motherboards to be out by now: Both Tyan and ASUS have 760MPX products on the market, and we keep hearing of an MSI K7D (not currently listed on the company's site), but that's about it. AMD claims that several other board manufacturers, such as Gigabyte, ABIT, and EPox, have 760MPX platforms due soon.

Meanwhile, neither the ASUS nor Tyan 760MPX products include any sort of integrated USB functionality, although the 760MPX lists USB as a chipset feature. When we asked, AMD confirmed that the AMD 768 Southbridge silicon does have an issue with the current USB implementation; although the flaw cropped up in only a few cases, vendors chose to go without direct USB support for now. AMD promises a fixed, fully USB-capable version of the 768 this quarter, as a simple drop-in replacement for upcoming motherboards.

That's fine, but USB has become a required component for both home and business PCs, and many key peripherals ship in USB-only format. That leaves vendors with the unhappy choice of shipping 760MPX boards now with add-in USB adapters or waiting for the new chipset revision to appear. Still, while this issue can be troublesome, it doesn't detract from the inherent attractiveness of this chipset.

With 760MPX motherboards shipping at prices only a bit higher than standard Athlon XP boards, this is the first time I've been personally tempted by a dual-processor desktop configuration. Although multiprocessing is not for everyone (especially everyone running Windows XP Home Edition), the key to the 760MPX is that it provides a low-cost, high-performance platform for both single- and dual-CPU machines. This allows unprecedented flexibility and cost savings for corporate buyers, and may even turn some home PC shoppers into twin-engine fliers.