↓
 

Computer Aid

Ph: 0402 133 866

  • Home
  • Blog
  • Contact
  • Web Services
    • Websites
    • SEO
    • Hosting
    • Domain Names
    • Portfolio
Home→Tags power suppy

Tag Archives: power suppy

Dead PSU

Computer Aid Posted on 18 February, 2006 by Luigi Martin18 February, 2006

Its funny how power supplies fail sometimes.

This one only lost the 12volts, so led’s on the motherboard and case were still lighting up. It had me fooled for a while. This is the first time that carrying a multimeter might have been useful. But since I don’t carry spare PSUs, It still would have involved a second visit.

Customer saying she once heard a bang, was the first clue that the PSU might be dead. Shining a flashlight into the PSU gave the second clue: a small cylinder (about 1 cm long & 0.5 cm in diameter) ie a blown capacitor, was resting on the bottom of the PSU casing.

Customer needed the PC quite urgently, so I replace her 420Watt PSU with my 350W for 1 day, until I get hold of some 450W units.

You might think using a 350W to replace a 420W is a bit dangerous, but I checked the volts and amps (a generic 420W seems to be only slightly more powerful than a 350W Antec PSU).

The trick with PSUs, is that Watts = voltage X current (amps). Since PCs need a combination of 5volts & 12 volts, its possible to manipulate the overall wattage.

Modern CPUs need a PSU that can supply a lot of current at 5 volts, and the need for 12 volts is generally just for hard disks, CD/DVD drives (ie not much), so you could have the following situation:

PSU1 is rated at:
12V X 20A = 240 W
5V X 40A = 200 W
total = 440 W

PSU2 is rated at:
12V X 25A = 300 W
5V X 28A = 140 W
total = 440W

so which is better for a PC?

PSU1 can handle a lot more current for 5V, and only slightly less current for 12V. Best for a modern PC with a power-hungry Pentium 4 CPU.

PSU2 has only reached 440 W by increasing the current at 12 V (at the expense of the 5V supply). This is only good if you have something that needs a lot of 12 Volts (eg a pentium3 PC with 4 hard disks and 4 CD/DVD drives).

Of course, there are also many other factors that are considered in designing a PSU, so the above description is somewhat simplistic, but it does give an idea of what to look for in a PSU.

Posted in Technical | Tagged power suppy, volts, watts

Archives

Categories

Recent Comments

  • Sue Jones on outlook error 0X800ccc0e while sending emails
  • Blair Newmann on AdSmartMedia advertising
  • Private Investigator in GTA on Divorce, consent orders, and superannuation splits: getting the wording correct

Tags

802.11g ADSL amd android bigpond broadband bsod defender dell email exitjunction firefox firewall gmail Google google contacts ie7 infection internet connection ISP laptop Linux m1188a ntldr is missing office 2007 outlook outlook express password power supply problems ram registry repair install sata scam slow telstra thunderbird usb vista wifi windows 7 wireless wordpress xp
Copyright © 2005-2015 Computer Aid
↑