Does the Pentium MMX Live up to the Expectations? — THG.RU

Introduction

15 days after its official release I eventually received my very own Pentium MMX 200. It was actually a kind donation of Erik Wagner from Nutek Systems USA, IL. I installed it on my system and it it ran straight away without any problems even at 208/83, 225/75 and 250/83 MHz. I am currently using it on my ABIT IT5V at 225/75 MHz with 64 MB SDRAM.

Before you start bombarding me with emails, asking why I used 205/68 instead of 200/66, or 166/66 instead of 171/86, I would like to explain the reason for it. I wanted to show most impressingly, that under some conditions the Pentium MMX 166 is even faster than a slightly tuned Pentium Classic 200 at 205/68. Hence I used the slowest Pentium MMX to compete against the fastest official Pentium Classic at turbo frequency.

Windows Applications

The most impressive performance Advantage of the new Pentium MMX CPUs are reached when running normal Windows applications. At the same CPU speed, the Pentium MMX shows a performance advantage of 16% over the Pentium Classic. This is only achieved by the new cache size and design, the branch prediction unit , the enlarged pipeline and all the other enhancements besides MMX. The performance advantage could be much bigger with image processing applications that are using the new MMX instructions.

For people who are using lots of Windows business applications, the Pentium MMX is certainly worth getting. Even the Pentium MMX 166 is already 5% faster than a maxed out Pentium Classic 200 at 205/68 MHz.

DirectX Applications

The first disappointment about the new Pentium MMX is its DirectX, especially its Direct3D performance. It is hardly any better than the performance of a Pentium Classic. This wasn’t expected by me, since MMX was meant to enhance DirectX directly. The Benchmarks were all run with the latest DirectX 3 drivers installed. Obviously the best improvement is seen in RGB mode. RAMP mode hardly shows any difference.

My Monster Truck Madness Benchmark didn’t show any improve over the Pentium Classic at all. This is to be considered as fairly sad, because lots of gamers were hoping to save the purchase of a 3D enhanced Video Card, like e.g. the Diamond Monster3D, due to the MMX enhancements of the P55C. Obviously so far we can forget about this. Either Microsoft has to improve their DirectX, especially Direct3D drivers, or the games have to use MMX instructions directly.

Currently Windows 95 gamers certainly hardly benefit from MMX at all and they can stick to the cheaper Pentium Classic for now.

I found an explanation for this problem, which doesn’t make MMX look too good for 3D freaks at all. It’s the missing 32bit SIMD multiply option of MMX.

Dos Games

The new Pentium MMX hardly shows any improvement for DOS Gamers. An increase of 2.5% is hardly worth mentioning. Even the other new architecture improvements of the Pentium MMX besides the MMX extension don’t bring us much of a difference in games like Quake or DukeNukem.

Hence DOS gamers will have to hope for games to soon use the MMX instructions or they happily can stick to their good old Pentium Classics.

Intel Media Benchmark

Intel’s new Media Benchmark was obviously written to demonstrate the superior MMX architecture. An improvement of almost 470% over the Pentium Classic at the same speed looks really impressive. Overall the benchmark promises a performance advantage of 63% over the Pentium Classic.

However, we obviously have to be careful with these results. This program comes from Intel and this means it’s running under ideal conditions. As long as an image processing program doesn’t use the MMX instructions, you hardly will see any improvement in these dimensions at all. c’t Magazine however showed, that with the latest Adobe Photoshop you can reach an improvement of up to 270% over the Pentium Classic.

The most embarrassing result for Intel in this benchmark is the 3D Graphics result. Although Intel certainly does everything to make the Pentium MMX look good, there’s only an improvement of puny 3.7 % in 3D Graphics. I would really like to know what that means. Can’t we even expect any 3D Graphics improvement for the future, when 3D programs are actually using MMX?

Guess Intel has to answer some serious questions here.

Conclusion

The new Pentium MMX certainly yields at least some increased performance out of your system. In current Windows business applications it already runs about 16% faster than the Pentium Classic. As soon as MMX instructions will be used in all applications, the improvement may be considerably higher, particularly in image processing applications.

For the majority of the Windows business application users the Pentium MMX is certainly to be recommended. Don’t forget that a Pentium MMX 166 is already faster than a Pentium Classic 200 under these circumstances and hence the Pentium Classic 200 should only be purchased if it is cheaper than the Pentium MMX 166.

However, for people who are using their computer mainly for gaming, which seems to be an increasing number, the Pentium MMX so far doesn’t show much of an improvement. If you are belonging to this group, you can either stick to your old system, or you could get a MMX approved motherboard now and wait until the Pentium MMX gets cheaper. The prices of the Pentium Classic will drop soon, so if you want to get a CPU for gaming now, you might as well take advantage of the cheaper Pentium Classic. After all this CPU still is a good performer, which kept us happy until Jan 8, 1998.

To Microsoft I would like to address the message, that they should do something about their DirectX MMX support soon. Intel won’t be too happy about the sad performance improvement under DirectX, but it would not be the first time, that Intel gets crossed by Microsoft. We only have to remember the problems a PPro has with the so called 32 bit OS Windows95. This was the reason for the tiny success of the Pentium Pro so far.

The 3D enhancement problem of the MMX instruction set seems to be more serious than expected. Here is an excerpt of an article from Microprocessor report, that is already 10 months old:

One drawback to MMX is the lack of a multiply or multiply-add for 32-bit operands. A fast 32-bit multiplier consumes four times more die area than a 16-bit multiplier, and Intel felt this feature was not worth the extra area. Besides, multiplication of 32-bit data can be performed using the standard integer multiply instruction. Although this instruction takes 10 cycles in the Pentium core and is not pipelined, it requires 4 cycles on Pentium Pro (and presumably Klamath) and, more important, is fully pipelined.

The integer multiplier, however, operates on the integer registers, not the MMX registers, and it cannot perform parallel calculations like the MMX units. Furthermore, there is no integer multiply-add instruction in x86. Because 16-bit precision is inadequate for advanced audio algorithms, such as wavetable sound, and for most 3D geometry calculations, the lack of a 32-bit multiply-add prevents these types of routines from taking advantage of MMX.

Cyrix and AMD will like the fact that so far only very few applications are taking advantage of MMX. The Pentium MMX release will push the software developers to create new MMX based applications, which probably will just begin to hit the market when their MMX CPUs M2 and K6 are coming out. That could be the perfect timing for them. Although Intel will soon release their new Klamath CPU, the competition for Intel will get harder. The M2 as well as the K6 are sounding pretty good so far. However, we will have to see if these CPUs will be able to live up to Cyrix’s and AMD’s promises. The past has shown that the great features of the Cyrix 6×86 couldn’t really hide the huge problems with this CPU. The 6×86 is only now starting to become mature, but a P200+ is now considerably slower than a Pentium MMX 200. Let’s hope that Cyrix and AMD have learned their ‘Pentium Lessons’ and that we will soon have a worthy competitor to the Pentium MMX and the Klamath.

One last thing I would really like to stress for the last time, so please read it carefully!!!!

The MMX capabilities of the CPU are completely untouched by the chipset! I still come across mails, where people claim you would need a particular chipset to fully use MMX. THIS IS NOT TRUE !!!! If some pseudo knowledgeable magazines try to make you believe this misinformation, then punish them by not buying them anymore! MMX is an extension to the CPU instruction set. It only can be used by software that’s using these new instructions! Of course Intel doesn’t try very hard to clarify this mystery, because Intel certainly likes you to buy new motherboards with the new upcoming 430TX Chipset. A MMX CPU doesn’t mystically get faster due to this new chipset. This chipset is NO ‘MMX CHIPSET’, since it doesn’t touch MMX at all! OK?