This was originally written for a magazine called PC Utilities many years ago. Processor articles date very quickly as new chips come out, but it's interesting to look back and see what things were like in 2004/2005.
Chip chat (an article written around 2004/2005)
PC users have always had a choice of processors to power their computers and weighing up the pros and cons of each one has been a perennial problem for buyers. There have been cheap, but low powered chips for those people on a tight budget, middle-of-the-range chips for the masses, and for those lucky few that can afford the exorbitant prices, there are always super powerful processors.
Up until fairly recently, the choice of processors has been fairly straightforward, with just a few models to choose from. Old timers will recall the days when you had a choice of a 25MHz 386SX or a 33MHz 386DX. OK, maybe the choice wasn't quite that limited, but there were rarely more than half a dozen chips to choose from. Any self respecting PC expert could tell you the chip names and specifications.
The situation has now got completely out of hand and both Intel and AMD offer such a large range of processors that it is bewildering. If you don't believe use, just go to the Intel and AMD Web sites where you will find around 150. If you want to buy a desktop or laptop PC, it is enough to turn any potential buyer into a quivering wreck. Faced with so many CPUs, how do you know what is best?
Perhaps AMD and Intel are trying to befuddle the buyer by offering so wide a range. You certainly have to wonder why there are so many variations. To make matters worse, Intel recently changed its naming convention and has adopted BMW-like model numbers, with 340, 520 and 730 models. Now you would think that a 710 would be better than a 510, but Intel says this is not necessarily true, and even though a Pentium D is a dual core Pentium, a Celeron D is not a dual core Celeron. What's more, dual core chips, which are supposedly the next big thing, are actually slower than traditional single core designs for many tasks. The market has gone mad!
Fortunately, we are here to clear these murky waters and hopefully, you will then have a better idea of what each processor does and which suits you best.
If we were to simply list the processors available from AMD and Intel, and give just a one or two sentence description, it would fill the article. Fortunately, most of AMD chips are listed here. If you want to see Intel's chips, go here.
It is difficult to know where to start when trying to unravel the mess that the processor market is in. If you buy an off-the-shelf PC, you often don't know exactly which processor you are getting and how good it is. For example, at the Dell site, a Dimension 2400 was being offered that had an Intel Celeron processor. We couldn't find it among Intel's current range and from Dell's brief description, it appeared to be an old chip and not up to the spec of the latest models. If you include old stock, the choice of chips must be approaching 200!
The best advice we can give is to look at the processor being offered in a PC and to try to find it at Intel's or AMD's Web site using the URLs above. After identifying the chip, there are then links to get further information, such as the FSB, cache size, and the socket type. You might not think that things like the socket type are important, but they are. A Celeron D 345 using the LGA775 socket has the execute disable bit, which is a useful anti virus and security feature, but the Celeron D 345 using mPGA 448 socket does not. The better chip is actually called a 345J and we have seen J appended to Pentium model numbers too. So chips with a J are better than those without.
The D also indicates higher performance, so a Celeron D is better than a plain Celeron. Old Celerons have a 128k cache and 400MHz FSB, but D models have a 256k cache and 533MHz FSB. (A cache is used to store frequently accessed data and the larger it is, the better a processor will perform.) The D model has streaming SIMD extensions 1, 2, and 3, whereas ordinary Celerons only have 1 and 2. SIMD adds powerful features for manipulating audio, video and graphics.
Cheap as chips
Any Intel processor with the Celeron moniker means cheap and cheerful. They are designed for the bottom end of PC supplier's range and besides being cheap themselves, they use cheap components too. There are Celeron's for desktop and laptop computers and if there is an M in the model name, it indicates that it is a low (electrical) power version for laptops.
There are ultra low power Celerons with model numbers like 373 that you would expect to be more powerful than a 360 or a 350, but it isn't. A 373 is clocked at 1GHz has a 512k cache, but a 350 runs at 1.3GHz and has a 1024k cache. The moral of this is that a chip model number is simply a number and it does not always indicate the features or processing power. You just have to look it up on the Web site.
AMD's chip names and model numbers are like a breath of fresh air and the range is comprehensive, but straightforward. The Sempron is at the bottom of the range and it is designed for PCs where a low price is more important than high power. You can tell how good a Sempron is by its speed rating. This is roughly the clock speed the chip would have if it was made by Intel. So a Sempron 2800+ should in theory offer a similar amount of computing power to a Celeron 2.8GHz.
If you are looking for a low cost PC, you should consider Celeron and Sempron processors, but don't expect them to be fast.
Socket to me
The way that a CPU plugs into the motherboard is important and it is a factor worth considering when buying a processor, motherboard, or an off-the-shelf PC. The reason is that it affects your ability to upgrade. If you want to boost the power of your PC, it is easier and cheaper to swap the processor for a faster model than to change the whole motherboard, and perhaps the RAM too.
For example, if you have a motherboard with an LGA775 socket that supports the Intel P4 with Hyper-Threading, chips are available from 2.8GHz with 1Mb cache to 3.8GHz with 2Mb cache. That is a significant increase in performance.
The dual core Pentium D uses LGA775 too and motherboards like the Gigabyte GA-8N-SLI Pro support both standard and dual core Pentiums. If you can track down the motherboard on the manufacturer's Web site, you will often find a CPU support list.
AMD Semprons use either Socket A or Socket 754. Some Athlon 64 processors also use Socket 754, so in theory you could upgrade a Sempron 2500+ powered Socket 745 PC to an Athlon 64 3700+. Similarly, Athlons from 3000+ to 4000+ use Socket 939. You do need to check the motherboard specifications though because the chips use different voltages and are other factors too. Obviously it is best to pick a socket type that gives you plenty of upgrade options.
In the early days of the PC, we would perform one task at a time. We would type a letter with a word processor or use a spreadsheet. These days, you might be downloading from the Internet, chatting via instant messaging, scanning for viruses, and defragging the disk. Computers need to perform several tasks at the same time, yet there is only one processor. How is it achieved? Windows handles all the tasks and constantly switches from one to another, so they all get a bit of CPU time. This is not very efficient and a better solution is to have two or more processors on the motherboard.
Multi-processor systems have been around for years and are supported by NT, 2000 and XP. Windows assigns tasks to different processors and they work simultaneously to get the jobs done more quickly.
Multi-processor systems are expensive, so Intel had the bright idea of simulating them. When Windows XP boots up on a P4 with Hyper-Threading, it thinks that there are two processors and assigns tasks to them like a multi-processor system. Of course, there is only one CPU, but a processor can switch tasks much faster than Windows can, so you get a more responsive system when trying to do several things at once.
Multi-processor systems are among the fastest computers in the world, but motherboards with two or more processors are too expensive to be mainstream. However, building two processors into one chip gives you the power without the price. The result is a multi-processor PC for the cost of a single chip system.
Intel's dual core Pentium D and AMD's Athlon 64 X2 are clocked slower than single processor systems, which means they are slower at performing single tasks. Most software is designed for a single processor, but a few programs, like 3-D rendering programs, video editing and MPEG compression software, can use multi-processor systems. These run more quickly than on single core processors. As dual core chips become common, software will be designed to take advantage of them. Just imagine Doom running on Dual Core!
An interesting side effect of Hyper Threading is that with a P4 dual core chip, Windows thinks it is running on a four-processor system because each core simulates two processors. The workload is then split four ways, which sometimes helps, other times doesn't. It's certainly interesting.
The case against the P4
Many experts reckon that the P4 is fundamentally flawed. It is powerful because it has a high clock speed and not because it is clever. An Athlon 64 clocked at 2.4GHz runs software as fast as a P4 at 3.4GHz or more. It also uses less power and produces less heat. It is clear that AMD currently has better processor technology, or has it?
When the P4 was first introduced, it was benchmarked against the current PIII and found to be slower. That didn't matter to Intel because it had designed a chip that would top out at 4GHz. As the clock speed rose, the chip could perform more calculations per second, but P4s consume too much power and produce too much heat. This development route is a dead end.
Processor experts reckon that PIII technology was actually better than the P4 that replaced it. Interestingly, when the Pentium M is examined, it looks a lot like a PIII. The top speed of the Pentium M is only 2.13GHz, yet it flies through benchmarks like a P4 running at over 3GHz. What's more, it uses so little power, it runs for hours on a battery.
Even more surprising, is that Tom's Hardware has found that a Pentium M 770 overclocked to just 2.56GHz outperforms every other processor on the market, including top of the range Athlon 64s and P4 Extreme Editions. Of course, a Pentium M is designed for laptops, but P4 PCs can use it with an ASUS adapter card (CT-479) and Aopen has desktop PC motherboards.
With around 150 processors to choose from, what we would recommend? Dual core processors are slower than single core when there is only one task to perform, but the difference is small and the benefits of dual core when multi-tasking are huge. Prices are currently high, but will surely fall.
In nearly all benchmark tests AMD's Athlon 64 X2 is faster than Intel's Pentium D, it uses less power, and produces less heat. It is the clear winner for those that can afford it. If you have a fairly new motherboard, you might be able to swap your current Athlon 64 for an X2 with only a BIOS upgrade.
You know what would really be the ultimate processor though? A dual core Pentium M. This chip is seriously underrated and it is no longer just for laptop PCs. A dual core version would fly!
1978 Intel 8086
Further reading: CPUs at Tom's Hardware