Current Cost: $167
Welcome to world of the 1GHz CPUs on a Value PC for the first time. For a "budget" PC, 1GHz certainly states right from the outset that this PC is going to be no slouch. For a mere $167, you can get an Athlon Thunderbird running at 1000Hz with a heat sink! With 256k of full-speed on-die L2 cache, this quick but not lightspeed Laserbeak of processors manages to fly as quickly as an equivalently clocked Pentium III. The Durons have good bang for the buck but the Athlon Thunderbirds are only slightly more expensive with much more performance.
Why retail? We've had e-mails asking us to include the price of a heat sink, and since the dangers of damaging your processor with a third party heat sink are very high, we recommend to the average user that you use AMD's heat sink. You also get a three year warranty thrown in. You can save a few bucks by getting an OEM processor and aftermarket heat sink, but we think it's easier just to go retail. Of course, if you plan on doing serious overclocking then you'll want more heat sink, in which case we suggest you get an OEM processor and save yourself a few dollars.
As for the classic Athlon, the old Slot A variety, avoid it. Though they have 512k of L2 cache, the cache runs at or lower than half the processor speed. This is not enough to keep the Athlon as fast as a Pentium III at an equivalent clock. As for Slot A Athlon Thunderbirds, which AMD said they would not release any on the regular market but did, avoid those as well as there are compatibility problems with many Slot A motherboards. Also, AMD says they will not be making any more Slot A processors, so if you buy a Slot A system now, you will have to upgrade your motherboard the next time you want to update your CPU. And to close the deal, the classic Athlon is only slightly less expensive than the Athlon Thunderbird, making it a bad value as well.
As for the Duron, it's only a little bit less expensive than the Athlon Thunderbird for a lot less chip. We see no reason to buy a Duron unless your budget is on the super Twiggy side. As it is, you can get a Thunderbird 850 for about the same price as an 850MHz Duron. For speed, future upgradeability and incredible value, stick with the Athlon Thunderbird.
See our High End Gaming PC AMD CPU recommendation here.
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Current Cost: $178
At 866MHz, the Pentium III provides excellent performance in business applications at a price point that won't kill the bottom line. SSE support dramatically accelerates floating point intensive business applications, including PhotoShop and Dragon Naturally Speaking, making these processor intensive applications easier to bear. It also helps in a few games, including those based on the Quake III engine. Its 256k of on-die full-speed L2 cache seems to help keep the performance up to par when you're running several tasks at the same time, and its use of a 133MHz front side bus helps keep data within easy reach of the CPU.
Overall, the Pentium III 866MHz processor provides the right performance at the right price to be our pick in the Value Business PC, especially when matched to a full-feature, integrated motherboard.
You may also want to consider getting an easily overclockable processor. Intel's Pentium III 700 can often overclock to 900MHz while running at a safe 133MHz FSB, and the slower Celerons, such as the 566MHz, can usually be adjusted to a 100MHz FSB gaining plenty of MHz.
As always with overclocking, there are no guarantees, but there are some things you can do to better your chances. Buy a good heat sink to keep the processor cool. Double check your case's airflow since an internal heat sink won't help much in a case that doesn't recycle its air, and make sure that the motherboard you use can up the CPU voltage. Often times a CPU that won't run overclocked at its default voltage will run fine with a 15% voltage boost.
See our High End Gaming PC Pentium CPU recommendation here.