The fine differences
Before we start rushing into numbers, we'll discuss the differences between some of processors and what they mean. Below is a picture of all the current AMD processors.
I'll take two fo each
The two processors that we're interested in are the Athlon MP and the Duron MP. Architecturally, both have the same Palomino enhancements, including cache optimizations such as trace and pre-fetch. Both have the same amount of level 1 cache at 128KB but the Duron only has 1/4th of the Athlon MP's level 2 cache at 64KB. Finally, both processors come with SSE instructions that AMD has dubbed 3DNow! Professional.
Why cache is important
Besides having raw clock speed, a processor's overall performance is largely dependant on how much cache memory it has. Cache is high-speed memory that holds frequently-used data very close to the processor. It is the first place the processor looks to for instructions before resorting to slower devices like system RAM and the hard drive. Cache also has a great deal more bandwidth than system memory because of its bus width and speed. Nowadays, L1 and L2 caches run at the same clock speed as the processor core, blistering past even 800MHz RDRAM. Cache memory is so fast in fact, that it is able to push terabytes of data through the processor relatively quickly. Compare this to today's fastest system bus and we begin to see the extreme importance of cache memory - the more cache, the faster the performance.
The amount of L2 cache is the main difference between the Athlon MP and the Duron MP. While the Athlon MP comes loaded with 256KB of L2 cache, the Duron only comes in at 64KB of L2 cache. Because of this, the Athlon MP should retain a sizeable lead over the Duron MP, more than enough to keep their respective market segments differentiated. It's also important to know that while the Duron has just reached 1.1GHz, the Athlon MP is soon going to be released at 1.5GHz and has been in distribution at 1.2GHz since June.
This puts the Duron MP in a very unique position. On one hand, it still doesn't have as much L2 cache as the Thunderbird but it does have improved caching techniques, SSE instructions and is fully sanctioned by AMD to run in a dual processor configuration. Because it's based on the Morgan core (Duron version of Palomino), we know that it has the capability to scale in core speed and most likely pass the Thunderbird core in the future.
We decided to test all the processors in a SMP setup because they are all capable of doing so. This way, it's easiest to determine what processor to get that would yield the highest value for SMP systems. We're also pitting the Duron MP against the Duron to see whether or not the improved caching techniques really help its performance. Lastly, testing the Duron MP against the Thunderbird will allow us to determine whether or not a Thunderbird still remains a relevant purchasing choice.
Dual processor mayhem
We know you're itching to see a complete review against single-processor and Intel Celeron/P4 machines; we'll have those out shortly, but thought it would be good to give everyone a quick run-down of what to expect in an equivalent-system setup.