mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > Hardware

Reply
 
Thread Tools
Old 2005-05-10, 17:02   #1
garo
 
garo's Avatar
 
Aug 2002
Termonfeckin, IE

22×691 Posts
Default Problem with display

Hi all,
I've been having some problems with the video display on my computer lately. It is an Athon 1.2GHz with an Epox K7A mobo and a Radeon 7000 video card.

I'm getting a whirring sound in the mobo along with moving horizontal black bands on the screen. It is not a monitor or a video card problem as I've changed both and the problem persists. Moreover, the black bands seem to be tuned to the whirring noise as when it stops for a second or two, the bands disappear.

I'm out of ideas here. Any suggestions?
garo is offline   Reply With Quote
Old 2005-05-10, 17:57   #2
PhilF
 
PhilF's Avatar
 
"6800 descendent"
Feb 2005
Colorado

2·11·31 Posts
Default

It sounds like something is breaking into oscillation, most likely the power supply.
PhilF is online now   Reply With Quote
Old 2005-05-11, 10:11   #3
garo
 
garo's Avatar
 
Aug 2002
Termonfeckin, IE

1010110011002 Posts
Default

Thanks. Could you explain in greater detail what breaking into oscillation means?
garo is offline   Reply With Quote
Old 2005-05-13, 17:09   #4
patrik
 
patrik's Avatar
 
"Patrik Johansson"
Aug 2002
Uppsala, Sweden

6518 Posts
Default

One of my computers have a similar problem. As long as Prime95 (actually mprime) is running, the computer is fine. But as soon as I stop it, or if it goes to zero CPU when it is communicating, I hear a high-frequency sound and see horisontal lines on the screen.

And I have a really old power supply in that computer, from 1998.
patrik is offline   Reply With Quote
Old 2005-05-13, 20:04   #5
PhilF
 
PhilF's Avatar
 
"6800 descendent"
Feb 2005
Colorado

2·11·31 Posts
Default

Quote:
Originally Posted by garo
Thanks. Could you explain in greater detail what breaking into oscillation means?
Here's the best way I can think of to explain it (power supplies 101)

The power supply takes the AC input voltage (which is 50 or 60 hertz), and changes it (rectifies and filters it) to a fairly high DC voltage. It then switches this DC off and on very fast (something like 20K to 50K hertz) so that it can be used to feed small transformers, which is what supplies the voltages we need (like 5V, 3.3V 12V, etc). Thus they are called switching power supplies.

These voltages are then rectified (changed back to DC) and filtered. Capacitors are used in the filtering process, and they are the most heat sensitive parts in the power supply. After time the heat causes them to begin to fail, which allows the high frequency switching noise to intermittently get through to the outputs. When this occurs all kinds of unpredictable things start happening. I think that is probably what is happening in your case, especially since you can hear it.

I hope this helps...
PhilF is online now   Reply With Quote
Old 2005-05-17, 12:56   #6
garo
 
garo's Avatar
 
Aug 2002
Termonfeckin, IE

22×691 Posts
Default

Thanks Phil for your explanation. However, I switched my PS for another new one but the same horizontal lines showed up. Moreover, the problem seems more severe when I use my old Radeon card as the display blanks out or stops responding arbitrarily after a few minutes of horizontal lines whereas with the Matrox I see horizontal lines but the display does not stop responding or blank out. I suspect the problem is with the motherboard instead.
garo is offline   Reply With Quote
Old 2005-05-17, 15:38   #7
PhilF
 
PhilF's Avatar
 
"6800 descendent"
Feb 2005
Colorado

2·11·31 Posts
Default

Hello Garo.

That is certainly possible. Motherboards have their own power supplies on them, PWM's or Pulse Width Modulators. They also use capacitors for filtering and stability, and often run hot. It is very possible one of them is breaking into oscillation (probably the one providing power to the AGP slot).

Good luck on tracking down your problem.

Last fiddled with by PhilF on 2005-05-17 at 15:39
PhilF is online now   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Inconsistent page display Uncwilly PrimeNet 8 2014-02-03 01:07
Stats won't display Unregistered Information & Answers 1 2013-06-29 15:40
How to display the date davieddy Forum Feedback 3 2011-06-12 00:45
Modifying Percentage-Done Display? Primeinator Software 4 2005-03-15 05:32
Trouble with display ThomRuley Hardware 3 2005-01-17 23:11

All times are UTC. The time now is 23:52.


Tue Oct 26 23:52:37 UTC 2021 up 95 days, 18:21, 1 user, load averages: 1.08, 1.31, 1.30

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.