Most of today's PC applications don't require greater processor performance. These applications run perfectly well on a Pentium 133 or equivalently rated alternative CPU. After all, it doesn't take a lot of processing power to satisfy the majority of today's most popular business and internet applications. Today's most demanding applications are games and graphics packages that utilize 3-D graphics or video. Applications such as Quake and Adobe Photoshop have a voracious appetite for CPU clock cycles and will consume as many of them as your operating system will allow. These types of applications demand raw processing power and can bring a lesser CPU to its knees. Fortunately for those who can't afford to spend a fortune on the fastest processor available today, these applications can be enhanced--within limits--by 3-D hardware accelerators. Although this is not the way the processor manufacturers want you to think.
3-D graphics functions can be divided between the processor and the graphics accelerator in many ways. With a simple 2-D graphics accelerator, all of the 3-D functions are handled in software. Included as part of Microsoft's Direct3D software is an emulation library that performs all of the required 3-D functions, using MMX if available. With most of today's 3-D accelerators, the rendering function--drawing filled triangles on the screen--is handled by the graphics accelerator, while the geometry function--manipulating the 3-D image's mathematical model to produce a set of 2-D triangles--is handled by the CPU. Geometry processing generally requires floating-point computations, so CPUs with good floating point performance do best on this task. The benefits of MMX show up when performing 3-D rendering in software. Once a good 3-D accelerator is added, however, the usefulness of MMX for 3-D evaporates.
As most of you know, the K6 and 6x86MX CPUs do poorly when they depend on software emulation for 3-D functions because of their weak floating point unit (FPU). The weak FPU of the 6x86 and 6x86MX is the number one complaint that I receive about these CPUs.
The 6x86MX and K6 CPUs do not perform as well as their Intel counterparts on applications that use MMX or floating-point (FP) instructions because Cyrix and AMD did not devote as much silicon to these functions as Intel did. The Cyrix and AMD MMX units can process only one instruction at a time while Intel's can handle two. All of Intel's CPUs have fully pipelined MMX and FP units.
MMX and FP weaknesses show
up as poorer performance on the ZD 3D WinMark 97. According to
benchmarks performed by PC Magazine, with
emulated 3-D, the 6x86MX-PR233 had only 63 percent and the K6/233
only 81 percent of the performance of the Pentium MMX/233. The
6x86MX MMX and FP performance is slower than the AMD K6.
The slow floating-point execution of the Cyrix and AMD parts make them great candidates for 3-D hardware acceleration. However, even when a good 3-D accelerator is used, the gap between the Pentium MMM/233 and the 6x86MX-PR233 remained a substantial 27 percent. Compared with a Pentium MMX/233, the K6/233 is still 7 percent short with a good graphics card. The difference between the 6x86MX and the Pentium II is even more significant, making the 6x86MX a pathetic choice for 3-D. I don't think that I am telling you hard core gamers anything that you don't already know.
If you care about image-editing performance with programs such as Adobe Photoshop or CorelDraw, avoid Cyrix and AMD CPUs completely and buy the fastest Intel processor you can afford. Graphics accelerators don't help with image manipulation.
To make the most of your money, consider buying a slightly slower CPU and spending the savings on MPEG or 3-D accelerators. These accelerators won't help performance on applications that don't use these functions, but they can provide a much bigger boost in 3-D and video performance than you would get from moving up one speed grade in a processor line. A $100 CPU with $500 in graphics hardware could yield a better multimedia system than a $500 processor with $100 in graphics hardware.
Be careful not to put a fast CPU with a slow 3-D accelerator. With a Pentium II, for example, a slow 3-D card can actually act as a decelerator. This is because the Pentium II, using the Direct3D emulation code with MMX, can render graphics faster than the hardware accelerator.
The battle for supremacy in 2D graphics acceleration is all but over, but the 3D wars are just beginning. Today's most advanced 3-D accelerators have fast floating pointing engines to handle geometry processing as well as rendering. These chips are used primarily in CAD applications, generally using the OpenGL API. Geometry acceleration isn't supported in the way most games are written, using Direct3D or other game-oriented APIs. In the next year or so, lower-cost 3-D chips with geometry acceleration will appear and the Direct3D API will evolve to support such accelerators more readily. Once these technologies are widely available and games are modified to take advantage of them, the floating point performance of the host CPU may become unimportant for 3-D. However, a lot of software will need to be rewritten before this will be the case.
In summary, if you are livid about the FPU performance of your 6x86 or 6x86MX, go out a spend some of the money that you saved on a blazingly fast 3-D card. Check out www.gamecenter.com for recommendations. That should help, but if your sanity depends on FP operations there is absolutely no substitute for an Intel processor.
This page has been accessed times
since Monday, September 15, 1997.
Sources:
pcmag.com