Intel Pentium 4 1.4GHz & 1.5GHz

SSE2: The other key to the Pentium 4’s success?

We mentioned earlier that one of the keys to the Pentium 4’s success will be ramping up production of higher clock speed versions of the processor.  Since the CPU will depend on its ability to have a high clock speed in order to order to remain competitive there should be a strong focus on that part of the Pentium 4’s development. 

There is another trick that Intel has up their sleeves and that is the follow-up to Intel’s Streaming SIMD Extensions (SSE).  As you’ll remember from our original Pentium III Review, the acronym SIMD stands for Single Instruction Multiple Data and it is a technology that allows a single instruction to be applied to multiple datasets simultaneously.  This comes in handy when dealing with fairly repetitive operations on different sets of data.  The example we’ve always quoted is the transformation of a polygon in mathematical space (a list of numbers) to a polygon in 3D space for display on the screen.  This process requires quite a bit of matrix mathematics which, to those that have had a basic introduction to matrix math, is highly repetitive.  SIMD-FP (Floating Point) extensions can help speed up this transformation process by taking the multiplication, addition and reciprocal functions required by the process and apply them to the multiple datasets involved at once. 

The first incarnation of SIMD instructions came with the introduction of Intel’s 57 MMX instructions back in 1997 which are essentially a set of SIMD-Int (integer) instructions.  The first incarnation of Floating Point SIMD instructions came in the form of AMD’s 3DNow! enhancements with the K6-2 processor.  However with the release of the Athlon, 3DNow! became virtually useless since the Athlon had such a powerful FPU in comparison to the K6-X series it was replacing.  Intel got on the ball months later with their first SIMD-FP extensions to the x86 instruction set and called them their Streaming SIMD Extensions, or SSE for short. 

Intel’s SSE instructions actually proved to impact performance considerably in certain situations.  And Intel is following up the success of SSE with the 144 new instructions that encompass SSE2.  These instructions offer an extension to MMX as well as SSE.  SSE2 enables the Pentium 4 to handle two 64-bit SIMD-INT operations and two double precision 64-bit SIMD-FP operations.  This is contrast to the two 32-bit operations MMX and SSE used to be able to handle.  The benefit of being able to handle two 64-bit operations through SSE2 is greater performance and in the case of SIMD-FP instructions, the ability to handle greater precision floating point calculations which is very important when dealing with more professional level applications.

The problem with SSE2 is that these instructions will require software support in order for them to be taken advantage of, meaning that previous applications will not benefit from them.  Luckily, as we have seen with SSE, Intel shouldn’t have a problem drumming up support for SSE2 and the next generation of applications and games should boast SSE2 optimizations. 

Another positive note for SSE2 is that AMD will be supporting SSE2 with their upcoming 64-bit processors that are due to be released at the end of next year or the beginning of 2002.  This should give the standard even more power behind it and will allow AMD to benefit from the same performance enhancements that will help the Pentium 4.

With the incredible power of SSE2 at the Pentium 4’s fingertips keep your eyes peeled at how gaming performance changes over the next few months.  A SSE2 optimized game could gain a hefty performance boost on the Pentium 4, as could just about any other SSE2 optimized application.  Luckily for AMD, Intel will do most of the work involved in getting the SSE2 instructions supported, AMD will just have to support the instructions and their next generation processors will be able to reap all the benefits.