Sempron CPU, The good and the bad

The first thing you need to know about Sempron cpu's is that the model numbering is much different than whatis used for the Athlon line of CPU's. A completely different set of benchmarks is used to determine the model (PR) number. This results in model numbers about 400 larger than the equivilent Athlon XP. AMD claims they did this to show performance difference between the Sempron and Intels Celeron line of CPU's. The fact that clock for clock they are priced a lot higher than Athlon XP CPU's leads me to another conclusion, but I'll let you be the judge of that. Since the Sempron name is used for both socket A and socket 754 parts, let's break it down.

The Good, Socket 754 Semprons

The socket 754 semprons appear to be a pretty good value. At the time of this writing there is only one on the market, the Sempron 3100+, and it is currently priced lower than the Athlon 64 2800+. Now since it would rate as a 2700+ model using the Athlon bechmarks, that put's it right in line with pricing. So as long as you don't plan on running a 64bit OS it's a very good buy considering how much it will overclock. In test the 3100+ has clocked to over 2500MHz from it's default of 1800MHz. Just make sure you have a MB that supports a PCI lock if you plan on overclocking. If you don't plan on overclocking, then a 2800+ would probably be a better choice. There's other details like cache size but they aren't really that important so I'm not going into them. If you want a socket 754 Sempron, there's no reason to avoid them, just remember to subtract 400 from the model number to get the A64 equivilent model number for price comparison.

Update March 2006
There are now many socket 754 Sempron versions. Some are now 64 bit enabled.

The Bad, Socket A Semprons

Socket A Semprons are a whole different story. They are nothing more than Athlon XP's with a name change and given higher model numbers because of the new benchmark suite. They did raise the default FSB to 166MHz, and this limits their overclocking ability on older boards and boards that won't support a higher FSB. I'm going to outline just one, the Sempron 2800+. The core of this CPU is currently a Tbred B core, but that could change to any of the others which really doesn't matter much as it will still be setup the same. The default FSB is 166MHz. That's 333FSB for the people that like marketing numbers. And the default multiplier is 12. Do the math and you come up with 2000MHz (12x166.67), the same as the Athlon XP 2400+ (15x133.34). So the only difference is the FSB speed and the multiplier. This would give the sempron a slight (3%) performance advantage over the Athlon 2400+, but they are basically the same cpu. Now consider that at the time of this writing, the Athlon 2400+ cost about $60 and the Sempron is about $90, and the price of a real Athlon 2800+ is only $80. The Athlon 2500+ Barton core is still the best overall socket A buy. At $64, it can easily be clocked up to XP 3200+ speeds with a MB that supports a 200Mhz FSB. I've only got one piece of advise about the socket A Semprons. Stay as far away from them as possible if you don't know exactly what you are really buying.

18 Oct. 2004