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[ The PC Guide | Systems and Components Reference Guide | CD-ROM Drives | CD-ROM Performance and Reliability ]

General Performance Issues - How Important is CD Performance?

The never-ending quest for speed, speed and still more speed has brought us CD-ROM drives that have gone from 1X and 2X to 12X, 16X and even 24X ratings. When it comes to hard disks, I always say "the faster the better, but watch your wallet". However, it is my (controversial?) opinion that in many situations the importance of CD-ROM drive performance is greatly overstated.

Your hard disk is used for booting up your machine, running most of your applications, holding your data, and even holding the swap file your operating system uses for virtual memory. Almost every PC user has applications, data, an operating system and a swap file on their hard disk. Because of all of these important uses, the performance of your hard disk impacts on virtually everything you do with your PC. CD-ROM drives are different. They can be used in many different ways, and how they are used depends a great deal on what the PC user primarily does with the drive.

If you are not doing a great deal with your drive, you really do not need the fastest CD-ROM drive on the market. While getting a faster drive will improve performance when using the drive, you aren't really going to notice it much at all if you aren't using applications that demand greater performance. In contrast, many people can live without a faster hard disk, but almost all will realize a noticeable improvement that will improve their computing experience on a daily basis.

There are also different ways to look at performance. In some applications, a lot of data must be transferred from the CD-ROM on a continuous basis; for example, if you are playing a video title from the disk. In this case the sequential read rate (also called the transfer rate) of the drive is more important than the random access performance (sometimes called access time). In other applications you don't need a lot of data streamed continuously, but small bits of data from various areas on the disk. Here, your priorities are reversed, and random access performance is more important than sequential performance, relatively speaking.

The table below shows some of the different uses typically made of CD-ROM drives and the approximate level of performance that they require. This is of course both general and subjective, but I think it makes a better guideline than the usual "get a faster drive!" nonsense that most people are constantly bombarded with:


Random Access (Access Time) Performance Requirements

Sequential Read (Transfer Rate) Performance Requirements

Driver Installations, Software Updates


Very Low

Software Installation



Referencing Archived Data

Low to Moderate

Low to Moderate

Executing Application Software

Moderate to High


Real-Time Database Work


Moderate to High

Multimedia (Video, Audio etc.)


High to Very High


Moderate to Very High

Moderate to High

There are many factors that play a part in determining performance levels and requirements as well. Caching is one; the use of a good-sized cache can "cover up" the poorer performance of a low-speed CD-ROM drive. Another is the fact that in many cases, data from the CD-ROM can be copied from the CD to the hard disk and used there. In this situation, the importance of the performance of the CD-ROM drive is greatly diminished.

For example, many games have many and/or large data files that are required while playing the game. However, most of these have multiple installation options, some of which will copy a significant amount of data to the hard disk. Since the hard disk is much faster than any CD-ROM, a PC with a fast hard disk and a slow CD-ROM drive can outperform one with a middling hard disk and a quick CD-ROM, in many situations. (Of course the drawback to doing a lot of big installations on games is that you lose a lot of disk space this way.)

Finally, remember that even though 24X CD-ROM drives are available cheaply today, there are millions and millions of older, slower CD-ROM drives already out in the market. For this reason, most manufacturers of software will ensure that the performance requirements for their titles are rather conservative. It is possible that a software company will put out a new package that requires a 10X or better CD-ROM drive, but if they do this they will give up a large segment of their potential market. Most software only requires about a 4X player or better, and in fact most software will work with 2X or better devices, albeit slowly.

Of course, there is usually nothing wrong with having a faster drive. Just remember that the super-fast ones cost more money, so make sure what you are looking at isn't overkill. At my office, I have installed about a dozen CD-ROM drives, because most of the PCs are older and did not have them. Most of these drives were 2X models, bought for $25 to $30 each, despite the fact that I could have bought 10X models for around $100 a piece.

Would I recommend a 2X drive to save $70 for the typical home user? Definitely not, because multimedia titles don't work well on a drive that slow. But for the business PC, where the CD-ROM gets very light use primarily for installing software, driver upgrades, mapping applications and the like, a 2X is just fine and I saved my company over $1,000. If you are buying a new drive and can get a 12X drive instead of an 8X drive for $15 more, why not? But buying a new 16X drive to upgrade a 10X drive is, for most people, a waste of upgrade dollars that could be better spent elsewhere.

Next: Rated "X" Speed, CLV and CAV

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