Watt's Up?


Q: I liked your March column on power supply issues. But I want to add a CD-RW drive and can't tell whether my 200-watt power supply can handle the extra load. I have a generic Pentium II system with a 2GB hard drive, CD-ROM drive, and a new 3D graphics card with 16MB of RAM. Any ideas?

John Galvin

A: Figure 4 shows a table of components found in PCs and the typical wattage requirements for each. Add the wattage values for all of your system's components. Then, to be safe, add 30 percent more (that is, multiply the total by 1.3) to calculate the minimum wattage rating for your power supply.

For example, if your system has a sound card and a floppy drive, you need a 178-watt power supply even before connecting a CD-RW drive. When you add the CD-RW drive, you'll need 39 watts more (30 X 1.3), but you'll lose the CD-ROM drive's 28 watts (25 X 1.3)-unless you plan to keep it installed. So your 200-watt power supply should suffice.

Or try the Power Supply Selector at www.pcpowerandcooling.com. If possible, use a power supply with a higher rating than you need. A power supply with a high wattage rating minimises heat production. And that's cool.

Kirk Steers


Category:Hardware
Issue: July 2000

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