Many Factors Affect Speed of a Pentium-Based PCs
Q: A friend told me that my Pentium motherboard accesses data at 32 bits versus 64 bits because I have only one RAM module instead of two. Is that true?
--David Brown via Internet
A: The answer to your question also leads to several other issues that readers have asked about, including motherboard design, the importance of cache memory and the difference between types of computer memory chips.
Your friend is wrong. There are a variety of factors that can affect performance of a computer equipped with a Pentium microprocessor, according to Howard High and Chris Lane at Intel Corp. But the size and number of RAM modules isn’t one of them. However, the total amount of RAM and the type of RAM does make a difference.
Let’s deal with the 32-bit versus 64-bit issue first. All Pentium chips and Pentium Overdrive upgrade chips communicate with the computer’s motherboard in 32-bit chunks. (A bit is a single 1 or 0 in the binary on-off language of computers, and eight bits combine to make a byte. Memory and storage capacity measurements are expressed in bytes, not bits.)
Inside the Pentium microprocessor, some tasks may be performed in 64-bit, or even 128-bit bursts, which may be the source of your friend’s confusion.
The architecture of the actual 32-bit connection between the Pentium and the rest of the computer, called a “bus,” is important for performance. The best performance is in computers equipped with the PCI bus, which incidentally was also designed by Intel.
Much of the software in use today is only 16-bit software, however, so it doesn’t really take advantage of the full performance potential of the Pentium.
The next performance factor is the cache, which is special high-speed SRAM memory that keeps the most-often-needed data ready for instant access by the microprocessor. The Pentium comes with 16 kilobytes of cache, called the L1 cache, built into the chip. An external L2 cache of typically 256 kilobytes or 512 kilobytes will enhance computer performance--but according to Intel’s Lane, the added performance of a 512kb L2 cache versus a 256kb L2 cache isn’t usually worth the cost except on multi-user servers.
RAM memory modules are available in several densities, most often ranging from 4 megabytes to 16mb per module. Lane said it doesn’t matter whether you use four 4mb RAM modules or a single 16mb module to get your memory.
But it does matter whether you use something called EDO RAM. The EDO stands for “extended data out” and describes a technology that allows the RAM chips to spew data out faster than standard RAM.
Richard O’Reilly, The Times’ director of computer analysis, will answer questions of broad interest in this column. E-mail questions to cutting.edge@latimes.com, fax to (213) 237-4712, or mail to Answers c/o Richard O’Reilly, Business Editorial, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053.
