Upgrading CPUs and BIOS, Part 1

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System builders—I have a few questions for you about the PCs you're working on:

• Are your customers complaining their screen redraws are taking forever as they run the big apps?

• Are your formerly white-hot PCs no longer powerful enough to run the latest versions of Windows or Linux distros?

• While you realize the price on the next generation systems which will run 64-bit and/or dual-core processors, DDR or DDRx2 SDRAM, PC Express, and SATA—will drop drastically in a year—would you still like to get some more performance (and extended useful life) out of the current systems you're working on until that happens? Especially if it doesn’t cost all that much?

If you answered any of the above with a "yes," then it's time to add memory and faster CPUs to your systems. All it will take is a couple of extra hours and a little bit of cash—figure $50 to $100 per PC—to bring your aging systems into the modern world.

This Recipe is for system builders working with sub-1000-MHz Athlon or Pentium 3 or 4 processors on boards that take 168-pin SDRAM. For machines older than that, I recommend that you instead purchase a new motherboard/CPU combination and populate it with DDR SDRAM. (For more on that subject, I recommend the Foner Books article How to Replace a Motherboard.) For everyone else, this Recipe is for you.

Why Add Memory?

Should you add memory or upgrade the processor? If you're working with a modern OS that takes advantage of more memory, such as Linux W2000 or Windows XP, and you aren’t already running 1 GB or more of memory, opt for the memory. In this case, bringing the computer up to an adequate memory level will make a much bigger difference on CPU-intensive operations than would even doubling the processor speed. Adding, say, 512 MB of memory will really speed any operations that are memory-intensive.

Adding memory makes a difference because the usual entry-level SDRAM configuration of 256 MB or less provided by vendors on older machines is no longer adequate for running modern operating systems, at least, not as quickly as they can run. While modern OSes can, in theory, run with 256 MB or even less, they really should have at least 768 MB available. Preferably, even more. This way, the data sets required to run the OS and applications will run in real memory—that is, within the available SDRAM, instead of being saved to virtual memory.

Virtual memory is a chunk of hard drive (often called the "swap file") that is used to emulate SDRAM for operations that don’t fit within the available real memory. This emulation works, but at millisecond speeds instead of the nanosecond speeds of SDRAM. Operations that "page" to and from virtual memory—that is, take a chunk of memory content and put or pull it into the swap file—are therefore much, much slower than those that fit into available real memory.

Also, without enough SDRAM, a great many operations require virtual memory, and the CPU ends up wasting most of its time waiting for the data it needs to perform operations requested by the user. The outcome: The user wastes time waiting for the computer. This, of course, is the main reason a user would want to upgrade their computer in the first place.

Before you add memory, check the motherboard manual for the type of SDRAM that works with your motherboard. Any SDRAM that matches your machine—for example, PC100, PC133, or DDR or DDRx2, unbuffered or buffered—should plug in. You can take advantage of extra SDRAM without concerns over configuration or exactly matching a processor or chipset.

Before You Replace That CPU...

Processor speeds are tricky. Doubling a system's CPU clock speed will not double the computer's overall processing speed for many operations. The reason: Many applications are limited by memory or even hard-drive speeds. So, to support a faster CPU, you may also need to add faster memory or even a bigger power-supply unit (PSU). To be sure, research the recommended power levels for your CPU from vendor sites or user forums. If power supply is a problem, a good bet is to look into mobile CPU versions, as they draw far less power than standard desktop CPUs.

Also, it's important to know that just because a CPU fits into a motherboard's CPU socket doesn’t necessarily mean the CPU will work. Always check CPU compatibility with the motherboard first. Also, sometimes when you replace a CPU, you will also need to replace the flash BIOS firmware. Another piece of information to research before you start.

But assuming you do want to upgrade a system's CPU, here are several points to consider before you start:

• Don’t attempt a CPU upgrade unless you can afford to replace the motherboard. An unsuccessful BIOS flash may turn the motherboard into a brick. This doesn’t happen often but it does occur. (I wound up flashing the BIOS a dozen times on my test machine for this Recipe, yet the computer still runs.) Be sure the PC's user understands that if there is a problem, they won't be using the system until the motherboard is properly replaced.

• Have the manual handy as you open the workstation case and get the exact revision number of your motherboard. If the manual says the CPU you have in mind is supported, proceed with confidence. But if the CPU is not explicitly supported, don’t try upgrading with it. Instead, find a CPU that is supported. If you can’t find a faster one that will work with the motherboard, simply upgrade the memory. At least that will give the user some performance improvement.

• Explore vendor or user forums offer information on the motherboard/CPU combination you have in mind to learn if anyone’s had problems with that CPU/motherboard combination. Some combinations of motherboards and processors simply do not work together, and these are the ones you want to avoid. The revision number should be on your motherboard or perhaps on the original order documentation (you still have it, right?).

  In general, successive revisions of the same motherboard model handle a progressively wider range of CPUs, though sometimes a BIOS firmware upgrade is required. Typically, revisions are made as the manufacturer gains experience with the motherboard's performance in the field. Revisions may involve different firmware, or upgraded versions of parts that determine internal timing or other parameters critical to operating specific CPUs.

  To begin your research on motherboards, Google these keywords (though in your actual search, substitute the keywords that fit the CPU/motherboard you have in mind): "motherboard model" and "CPUmodel speed." For example, here are the terms I used for my Google search (with quotes): "M810LR" and "Duron 1800."

• Look online for a user FAQ on the motherboard you're working on, and explore for a list of recommended processors. User FAQs are often far more helpful than a vendor's official documentation.

• From your research, find out in advance if the system's old memory is fast enough to support the front side bus (FSB) speed the processor you plan to use runs at. Also find out if you'll need a heavier PSU to handle the new chip. For example, AMD recommends a minimum of 3.3V at 28A to run their current generation chips. If your PSUs can't supply that much, you'll need an upgrade.

• Make sure you're comfortable working from a DOS command line. You'll need this for BIOS flash programs. If you aren't comfortable at the DOS command line, don't do a CPU upgrade unless you’re certain you won’t need to do a BIOS upgrade--or if you've got expert help available locally to bail you out if you get into trouble. (I'll discuss BIOS upgrades in greater detail in Part 2 of this Recipe next week.)

If you've gotten this far, stop and add up the upgrade budget to decide whether it’s worthwhile proceeding with the upgrade. The upside? While your competitors are waiting for prices to drop on next-generation motherboards/CPUs, your systems will already be running substantially faster. The downside: It is possible to put all the pieces together "correctly" for a CPU upgrade, only to find the system won’t run. This is usually due to a BIOS incompatibility, though sometimes it may be due to the CPU-support chipset incompatibilities I discussed above.

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