I suppose it was inevitable. Since outlining the differences between CISC and RISC, several asked about the ongoing battle for supremacy between the big two of mainstream x86-based processors: AMD (Advanced Micro Devices) and Intel. To gain perspective, I think we should take a brief look at history and then discuss how these two companies differentiate their products today.

In the early days, Intel and AMD maintained a technology licensing agreement. Basically, this meant that when Intel developed new processor technology, AMD was entitled to use it. To this end, both companies produced extremely similar products, with AMD focusing on producing cheaper offerings than Intel. Feeling the pinch of competition, Intel ended the licensing agreement with the Socket 7 line of processors (the original Intel Pentium and the AMD K6). With these CPUs, the two companies diverged.

Early differentiation was in the core architecture of each brand, with each developing distinct internal command sets. It began with MMX (Multi-Media eXtensions) from Intel and AMD’s 3D-Now! Each continued to extend these commands further, basing much upon SIMD (Single Instruction, Multiple Data) commands which accelerate system performance in graphic intensive environments. As mentioned in October, these technologies have gradually produced large differences in the processors, much in the way core differences make RISC and CISC architectures dissimilar. AMD’s current focus is to process more commands per clock cycle, while Intel’s is on producing chips with the highest internal clock speeds.

Closely tied to the core architecture is the physical construction of the processors. After the initial divergence, Intel quickly moved from socket to slot based processors (Slot 1), claiming the larger package provided for expanded features (like room for more on-chip memory), while being easier to cool and upgrade. AMD followed suit, releasing their own version (Slot A), the first product designed after the end of the licensing agreement. 

Each company is now refining the production of their chips, moving from the 0.18 to the 0.13 micron process. The smaller number correlates with manufacturing smaller chips, which run more efficiently and can simultaneously contain more transistors — translating directly into more processor power. Meanwhile, decreasing the size allows more space for increased amounts of L2-Cache on the processors. When combined with new motherboard chipsets, these processors support higher bandwidth FSB (Front Side Bus) speeds with faster external memory support through RDRAM (Rambus) and DDR (Double-Data Rate) memory architectures.

At the beginning of the year, Intel introduced its Northwood CPU core, at 0.13 micron with 512KB of L2-Cache on a 100MHz FSB supporting 400MHz RDRAM. The Pentium 4 2.2GHz, based on the Northwood core, outperformed AMD’s Athlon 2000+, which was actually a 1.6GHz processor based on AMD’s Palomino core, at 0.18 micron with 256KB of L2-Cache on a 133MHz FSB supporting 266MHz DDR RAM. By March, AMD released the 2100+, which proved to outshine the P4 2.2GHz. Intel answered in May, taking another leap by moving to the 133MHz FSB and 533MHz RDRAM, with the P4 2.533GHz. This processor beat the 2100+ in all tests. In June, AMD made its move from 0.18 to 0.13 with its Thoroughbred core and was able to reach the same performance marks as higher-clocked P4’s, demonstrating that clock speed was not the only measure of performance. However, these changes failed to attain the overall performance of Intel. So, in August, AMD made adjustments to their CPU core again with the Athlon XP 2600+, allowing them to surpass Intel. But Intel quickly countered with its P4 2.8GHz, which bested AMD.

So, what’s my opinion of the two? That competition is healthy and the battle is far from over. Projections suggest the Athlon XP 2800+ can regain the performance lead. The FSB will increase from 133 MHz to 166 MHz, fully supporting DDR 333MHz memory. This brings performance up to the level of a top P4 model with 533MHz RDRAM (named PC1066). AMD will also be increasing their level of L2-Cache to 512KB. Unfortunately, AMD won't be able to deliver these CPUs until next year — so Intel should retain the performance title a little longer.

Based on the maturity of each processor, and increasingly stable motherboards, I never hesitate to recommend either to customers. With performance so close, it’s more often a matter of brand loyalty than anything else. Though I sometimes have a hard time listening to my own advice, I generally find the best value when buying two levels below the latest offering (whichever brand you choose). This means purchasing a 1.7GHz after the release of the 2.0GHz model may give you the most performance for your dollar. Raw performance comes at a premium.

Also, with designs changing every day, purchasing top-of-the line is a quixotic endeavor. I suggest setting a budget and buying the beefiest overall system within that budget. Put the motherboard, memory, and other desired components together first. Then check the compatibility of these components, purchasing the processor that fits your system. If it’s Intel—great! Otherwise, AMD is always a viable alternative.