Computer PSU

The Power Supply Unit

If you build your own computer or modify a machine you got, its easy to overlook the power demands of your system. Modern computers are power hungry and you should ensure your power supply unit is up to the job.

Typical component power demands:

Component Requirement
Motherboard 20 - 30W

CPU Pentium 2 30W

1.0 GHz P 3 34W
1.7 GHz P 4 65W
1.4 GHz Athlon 70W

RAM 8W per 128MB

Graphics Card 20 - 50W

Hard Disk Drive
7200rpm IDE 5 - 15W
7200rpm SCSI 24W
10,000rpm SCSI 10 - 40W

50x CD-ROM 10 - 25W
12x DVD-ROM 10 - 25W

12x CD-R/RW 20W
12x CD-ROM 12W

PCI Card 5W
10/100 NIC 4W
SCSI Ctrl PCI 20-25W
SCSI PCI card 5W

Floppy drive 5W

This should provide enough info to check your PSU is up to the job.

Total the component values and work on 75% - 80% capacity. Leave a little in reserve for surges or unusually heavy demands.