iYAN inside! Online Index HardwareThe SSE instructions
The 3D acceleration of the Pentium III
What is SSE
presented the Pentium with MMX. For the first time the original x86 instructions were edited, resulting in 24 new multimedia instructions that boosted multimedia performance in some applications. SSE (only available with Intels Pentium III) is similar to MMX, only more advanced. These new instructions follows modern trends, based on huge sales of 3D games and graphicscards. SSE accelerates 3D applications, that use these new instructions, providing more framerates and faster calculations (with enhanced effects). Also some internet websites and speechrecognizing programs can benefit from SSE. But that shows also the handicap of these new SSE instructions; programs must use them to show any improvement. Otherwise the difference is neglectable.
How SSE works
SSE stands for Streaming SIMD extensions. An old term that was previously used for SSE is KNI; Katmai New Instructions (Katmai was the codename of the Pentium III). Besides 70 new instructions (almost four times more than MMX had), the Pentium III also has a new mode: SIMD (Single Instructions, Multiple Data). This mode makes it possible to use several instructions in parallel (so, at the same time), which results in a reasonable performance boost. According to Intel, MMX would also benefit from this, but that isn't very noticeable.
Does SSE work immediately on a Pentium III machine?
No, not really. Previously it was assumed that Windows 98 needed a patch to work with SSE. Now it seems that is obsolete, because it already had native support. Windows NT does need a patch however, together with Service Pack 4, to use SSE. Everyone who owns a Pentium III and Windows 98 can not use SSE immediately, however. First you need a BIOS upgrade, that recognizes the Pentium III (it seems an old BIOS might work - calling it a Pentium II 500 - but we recommend to use an upgrade to prevent problem). Second, you need to install DirectX version 6.1 (which is the only version with SSE support). And third you need optimized drivers for your videocard. In our case (ASUS V3400TNT) we downloaded new nVidia TNT drivers, as there was no update available from ASUS, yet. That's it, in exception of some other software patches. A few months from now, SSE will be used more in new released software. In previous software there is no SSE support implanted. Sometimes there are patches available to make the software take advantage of SSE, like Adobe Photoshop 5. According to Intel, SSE (fully configured, as mentioned above) will also speed up existing software that use DirectX. During our testing, this appeared to be 1% increase in speed at the most, so it is almost neglectable.
Some benchmarks
It took quite some blood, sweat and tears to find some benchmarks that show the difference between an Pentium III with SSE enabled and disabled. We've downloaded more than 200Mb of software (almost broke now), such as game-demos, patches, benchmark utilities and other software. The program that showed the SSE power the best was 3DMARK99; a 3D benchmark utility. 3DMARK (www.3dmark.com) is a program with various 3D demos, including two fictional games like this "RACE". Especially this part showed what SSE might enhance in games. The framerates (per seconds) scored 22% more with SSE enabled. But I must add that is was the only test with such a high difference. It does indicate that games can benefit from the new instructions. Other (real) games that we've tested were Descent 3 and Heavy Gear 2, which are on the list of SSE optimized software, on the Intel website. We noticed no real difference however, but this might be because we used demo versions (with no SSE support?). Information from another source indicates the game Dispatched scored 80% higher framerates with SSE, but the details in the game were of lower quality. I wouldn't call that an objective improvement…
The results on the left are from the complete 3DMARK test (all on nVIDIA RIVA TNT) like the graphic on the right. Our testsystem is printed in translucent colors, the other figures are averages from unofficial scores from 3DMARK. Our testsystem scored higher than the averages, in all cases. We also see a reasonable increase in performance in overal performance weather the system uses SSE or not. We must add that CPUMARK99 is well-known (and acknowledged by Intel) because of its Pentium III optimalisation. It is one of the few programs were the power of SSE is visible. In a half year from now, we will know what the benefit in software really is, when games will support non-SSE, SSE and even AMD's 3DNOW (=similar instructions), making the improvements visible and comparable. On this day, we can't really compare (in an objective way) to other systems.
SSE and other software
Until now, it seems SSE is specially created for games. This is not the case, however. The best example is the SSE patch for Adobe Photoshop 5. The difference between 5 (without SSE) and 5.02 (with SSE) is quite big. We have tested the 5.02 ourselves, but we're using this benchmark to show a clear difference with a 450MHz Pentium II and III. In this graphic a low value is a better score; they represent the time that is needed to calculate filters, enlargements, (un)sharpening, etc. It is obvious that Photoshop users will benefit a lot from SSE. A lot of calculations only use half of the regular time.
SSE: judgement
Intel claims SSE will also benefit internet purposes. This sounds too gooed to be true. An internet connection will not be any faster with SSE, but it can improve search routines on websites that use SSE. This is also the weak point of SSE... At the moment, support is very rare. After a while there will be more and more patches and new programs that include the usage of SSE. AMD has made a similar step in May 1998, with 3Dnow, which also improves 3D performance (when the instructions are used). 3DNow is used in the popular K6-2 and on this day a reasonable amount of software and drivers support it. At an introduction of new instructions, it takes a while before programmers will use it in their programs. And they will only do that when there is a demand (so, when it sells good). It takes a few months to see what will happen.
Intel makes a good attempt to go along with the need for 3D acceleration. It looks like it is superior to 3DNow (mainly because of SIMD), but AMD had a headstart of almost a year. On this moment SSE is a must voor people, working with 3D applications like Photoshop. It isn't really an alternative to 3D cards. It's a pretty nice extra feature, for a steep price, however...
