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Reviewed by: Trevor Flynn [09.13.04]
Manufactured by: AMD

 

The Budget Shootout

In a perfect world, computer hardware would be free to all who wanted it, and everyone of us would be running the high end system of our choice. The only thing that would hold us back from having the best of the best would be our own laziness (ohhh man...another newer/faster video card...but I JUST upgraded last week!). But let's face it, a perfect world this is not.

While there is still the enviable few who are always able to stay on the cutting edge of the hardware curve, most of us are limited by either our wallets or perhaps our wives' strong grip on our wallets. For those of us in these situations we are resigned to endlessly searching for that hidden gem of a component which will allow us to gain high end performance on a low end budget.

Without a doubt, the AMD Athlon 2500+ processor has been one of the best bang for the buck processors to come along perhaps since the old Celeron 300A. Many of the original Barton based chips can easily be bumped up to 3200+ speeds while running at stock voltage. Unfortunately after finding numerous instances of dealers unscrupulously selling 2500+ chips at 3200+ prices AMD was forced to lock the multiplier on most current Barton 2500+ chips.

No fear though, next came the mobile version of the Barton which, although came stock with a much lower FSB (133mhz), was able to achieve some massive overclocking results thanks to its low power requirements and wide range of available multiplier settings.

And then now, AMD adds yet another option into the mix by releasing the new Tbred B based Sempron 2500+. Which chip will give you the best performance at stock speeds?  Which chip is best for overclocking? And most important for the frugal majority, which chip is the best bang for the buck?

The Breakdown

From Left To Right: Athlon XP 2500+, Mobile Athlon 2500+, Sempron 2500+

  AthlonXP Mobile Athlon Sempron
PR Rating 2500+ 2500+ 2500+
Frequency 1829 MHz (11x166) 1862 (14x133) 1743 (10.5x166)
Core Base Barton Barton SOI Tbred B
Cache L1: 128K
L2: 512K
L1: 128K
L2: 512K
L1: 128K
L2: 256K
Process Technology 0.13nm 0.13nm 0.13nm
Thermal Rating 68.3W (1.65V) 45W (1.45V) 62W (1.6V)

A couple points of interest here when comparing the three 2500+ chips.

- The Mobile 2500+ has the highest overall frequency but also has the lowest FSB which when all things are equal should hurt it in stock performance.

- The Sempron only has half the L2 Cache compared to the two Barton based chips. This will hurt the Sempron's performance; see below for more details as to why.

Cache, What's It All About

To use a very common analogy, let's think of the CPU as a production facility and Cache as a series of warehouses. Land around the production facility is VERY expensive and therefore we only have a small warehouse right on site, with a larger one a little bit further away. (L1 and L2 cache).

The most commonly used materials are stored in the first smaller warehouse, but if for something isn't found in that first one, we have to then take a trip over to the second larger warehouse which takes more time and production slows down. If we need a material that isn't used very often, or which hasn't been used for a long time then we have to drive all the way into town to pick it up (main memory) which takes an even longer amount of time.

This is obviously a very simplified version of how Caching works but I think it's effective at getting the point across. With CPU speeds constantly outpacing Memory speeds cache has become very important in processor design with extremely complex algorithms being developed to determine what data/instructions are stored in what level of cache, etc. Without some implementation of Caching principles CPU processing speeds would never be able to effectively exceed the speed of the memory devices which were feeding data to it. I did not invent the analogy used above and am absolutely not the first person ever to use it.

Model Steppings Used

Included specifically for those of you who live and breathe CPU stepping codes. You know who you are....

From Top To Bottom: Athlon XP 2500+, Mobile Athlon 2500+, Sempron 2500+

The Test

We put all three 2500+ rated chips through a plethora of performance benchmarks in order to see which of the three will give us the best performance for our dollar straight out of the box.

Now there is mention that the Sempron 2500+ rating is actually in comparison to relative Intel Celeron CPUs (since they are after all it's main price point competition), but after years of having AMD promise me and the world that it's performance rating system was based on some mythical Thunderbird processor and NEVER the competition I don't buy it. You're not allowed to rate two chips at identical 2500+ speeds without so much as an asterix and then tell that they're not supposed to perform similarly. The same goes for the Mobile Barton Chip.

Test System

Motherboard: Soltek SL75-FRN2-L (Nvidia Nforce2)
Memory: 1GB OCZ PC3500 EL (running DDR333) 2.5-2-3-8
Video Card: Celestica Radeon 9600XT
HDD: Maxtor 40GB ATA133
HSF: Gigabyte 3D Rocket Cooler Pro
Windows XP SP1, DirectX 9b, Nforce 3.13 , ATI Catalyst 4.6

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