Upgrades: Right on the Money

CPU Boost

I can't seem to find a decent guide to upgrading processors. My main problem is that I don't know what processors are compatible with my computer. Then again, would a CPU upgrade be a good idea for me at all?

Al Highsmith, former electronics technician, Umatilla, Florida

This is a common question, so we tested three different PCs with several CPU upgrades. In a few cases, the speed boosts were remarkably satisfying. But before you check the benchmark results, you need to determine whether your computer is a likely candidate for an upgrade in the first place; and then you must decide whether opting for a motherboard upgrade or for a packaged CPU upgrade--or just swapping in a raw new processor--would be the best course of action.

To determine whether to upgrade, you often need more information than the class and clock speed of your current CPU--and in any case, you should verify the CPU you have. So start by downloading, installing, and running a system information utility from PowerLeap or Evergreen Technologies, the companies that manufacture the processor upgrades we tested. (Don't rely on the General tab of the System Properties dialog box--it doesn't always positively identify your CPU.)

Once you've verified the chip and clock speed, it's time to see if you qualify as an upgrade contender. Your CPU will fall into one of three groups:

• Group 1: Intel Pentium or 486; AMD K6; or earlier. So you want more speed? Buy a new computer. CPU upgrades for these oldsters are available, but you'll probably be left with a slow hard disk, an old graphics card, and too little memory. Upgrade everything you need, and the components will cost more than a new PC. Give that old hand-me-down system to someone you love. Or hate.
  
  
• Group 2: Intel Pentium II, Pentium III, or Celeron; AMD Athlon, or Duron. You may already be a winner. The (very) general rule: If you can find an inexpensive processor upgrade that will double your machine's original clock speed, go ahead and give it a whirl.
  
  
• Group 3: Pentium 4 or AMD Athlon XP. These are fast already. You may be able to find a compatible CPU with double the clock speed, but it will be expensive. Probably too expensive. Look at upgrading other components of your system first.
  
  

Some further refinements for group 2 members: If your current Pentium III, Celeron, Athlon, or Duron runs faster than 1 GHz, the advice for group 3 also applies to you: Even if you can double your clock speed, that isn't the same as doubling your system's performance. Try to squeeze another three to six months out of your current system, and then opt for a motherboard swap or a new PC.

Motherboard, Raw CPU, or Packaged Upgrade?

For group 2 members, the classiest CPU upgrade is a full motherboard replacement. You'll have the widest possible choice of CPUs, and all the speed advantages of new motherboard technology. It's not an upgrade for beginners to try, but motherboard prices are quite low--between $50 and $250, depending on how cutting edge you want to get. You'll need new memory and a new CPU, as well--raising the practical price for this upgrade to the $300-to-$700 range (see September's " Motherboard Buying Guide").

Is that too rich for your blood? Then the cheapest, simplest thing to do is to replace your current processor with the fastest CPU your motherboard will allow. First, you'll have to identify your motherboard's chip set and, in some cases, the motherboard revision number. PowerLeap's free CPU Control Panel utility, extracts all this information and more, including the processor socket or slot type and even the CPU serial number (although you won't be needing that detail).

With this data in hand, call your system manufacturer's tech support and find out which CPUs are compatible with your system. You can also visit your motherboard vendor's Web site and see which processors will work with your motherboard's make, model, and revision. If you can buy a CPU that doubles your clock speed (or thereabouts), great. For example, Intel's D810E2CA3 motherboard accepts a wide range of processors, beginning with the 400-MHz Celeron and ending with the 1-GHz Pentium III, which you can buy on the street for about $120.

All too often, however, the range of supported CPUs is limited. For example, certain revisions of the Intel SE440BX-2 motherboard, which shipped in millions of Pentium II and Pentium III systems, support Pentium III chips only in the 450-MHz to 600-MHz range. Worse, the SE440BX-2 uses the old Slot 1 CPU connector--and nobody outside of EBay sells plain-vanilla Slot 1 CPUs anymore.

Fortunately, packages from companies like PowerLeap and Evergreen Technologies can widen the scope of available CPU upgrades. For example, people who own SE440BX-2 motherboards have several Slot 1 upgrades to choose from--topping out with a fast 1.4-GHz model from PowerLeap. Basically, packaged upgrades contain circuitry designed to fool the motherboard into working with CPUs faster than the BIOS and the chip set were originally designed to accept. There is one big caveat, however: As our lab discovered, compatibility problems make these prepackaged upgrades a hit-or-miss affair.

Nice Speed If You Can Get It

First, the good news: When these babies work, they really cook. An old 350-MHz Pentium II from Quantex enjoyed the biggest boost, posting a PC WorldBench score 57 percent faster with Evergreen's $170, 1.1-GHz Performa III installed. (See the " Upgrade Processors" chart.) An old 450-MHz Pentium III Gateway Performance outfitted with a $170 PowerLeap PL-iP3/T 1.4-GHz Celeron upgrade did nearly as well, logging an awesome 56 percent speed increase. As predicted, however, anything less than double the clock speed seems hardly worth the price: When we upgraded a 733-MHz Pentium III Dell system to Evergreen's 1.1-GHz Performa III, we saw a mere 12 percent boost.

And now for the bad news: PowerLeap could only assure us that its packaged upgrades would work in one of the three systems we tested, and we didn't stumble upon pleasant surprises when we tried them in the other two. The moral here: You should check the lists of systems that the manufacturers have explicitly certified as compatible on their upgrade Web sites, or even better, submit your system details via e-mail so the companies can give you a thumbs-up or thumbs-down before you buy. If all else fails, both PowerLeap's and Evergreen's products come with a 30-day money-back guarantee.