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Putting a technology demo machine through its paces can be quite a challenge, especially when its closest competitor is 33MHz slower and hasn't-unlike our prototype K6 systems-gotten more fine-tuning than a Grand Prix race car before the big race. But taken as a promise of things to come, can the K6 outperform its Intel siblings? Probably.
The two K6 systems we examined were identically configured, one running Windows 95 and one running NT 4.0 Workstation, without additional Service Packs. We checked performance against that of a standard 200MHz Pentium Pro, the Quantex QP6/200 WS-4. The K6 and Quantex systems were maxed-out configurations, to be sure (see table below), and the K6's whopping 1MB level 2 cache-vs. 256KB on the Quantex-accounts at least in part for the K6's superior test scores.
On the NT system, the K6 processor pumped out a startling three-pass average of 457MIPS and 139MFLOPS, the highest scores we've yet seen from a single x86-compatible-processor system-10 percent and 25 percent faster, respectively, than Pentium Pro.
Using the same video card (the Matrox Millenium) as the Quantex system, the K6 made its mark in video as well. Its 138Mpixel-per-second average scorched past the Pentium Pro's typical 105.7Mpixels per second under Windows NT, a difference of a bit more than 30 percent. Windows 95 tests showed the K6 gaining 43 percent in video performance over the Intel chip. We kept resolutions and color depth set low-800x600 at 256 colors-for comparison purposes, but the K6's ultra-fast performance held all the way through 1024x768, 24-bit resolutions.
The K6 made a fine showing in our application macros, too, completing our Microsoft Word 95 macro in 5.3 seconds under Windows NT and 7.7 seconds in Win95.
Having the K6 around made a difference to our Microsoft Excel 95 macro, too. Its 3.3-second average completion time under NT 4.0 proved to be faster than the Quantex's 4-second score. Again, K6 improved Excel's performance under Windows 95, running 9 seconds for the Pentium Pro and a faster 7.3 seconds, a 23 percent improvement, for the K6.
We breezed into cached-disk tests expecting an easy victory for the K6, since all that extra cache and faster processor should result in greater data throughput. Unfortunately, this was the one area where the K6 fell short. While scores under Windows NT 4.0 edged out the Pentium Pro, the situation reversed in our equivalent tests using Windows 95. The K6 was half as fast. However, we believe the problems may be driver-related rather than directly the fault of the chip. By the time real K6 PCs ship, these differences may be at least partially resolved.
AMD brags that the K6, unlike the Pentium Pro, is designed to execute 16-bit code without the well-known performance hit that Pentium Pro processors suffer. It's tough to judge that using these prototypes, but our tests seemed to bear out their claim. Processor scores for the K6-MIPS and MFLOPS-were virtually identical under both operating systems.
We chose not to run Intel's MMX benchmarks on the K6 machines, since it seems dubious at best to use one manufacturer's benchmarks to measure the performance of another's processor.
Software that supports MMX instructions contains a line of code identifying the chip as an MMX processor. AMD told us that the K6 is fully MMX-enabled, so any MMX instructions should simply treat the K6 as they would any Intel MMX CPU. We haven't had the opportunity to check that out ourselves yet, but will do so shortly in an upcoming round-up of MMX-enabled systems.
In the meantime, remember that the vast majority of software out there remains MMX-ignorant. By the time Intel's MMX technology becomes a common part of any software spec sheet, developers will have had time to adjust, so if there are any compatibility problems, they would probably be temporary at best.
Of course, the K6's juiciest market will be the PC econobox, and with the high cost of cache memory it's doubtful that you'll see our demo's 1MB worth of level 2 cache there. Given the more probable 256KB cache, we'd likely have seen scores closer-taking the difference in clock speed into account-to those of the 200MHz Pentium Pro. Still, these tests indicate the AMD offering will be a serious power contender in the high-performance desktop market. It's definitely worth considering if you're in the market for a new PC.