Strange Screen Corruption Problems
Posted by: mharttpalmer on 21 September 2006
I have had a problem with my PC for several weeks now, which is confusing the hell out of me as I don't seem to be able to get to the bottom of it:
I'm running quite a powerful system, as I use it for quite a lot of audio recording/editing, as well as music engraving and arranging.
My system is as follows:
AMD Athlon 64 X2 4200+ Processor
Asus M2N32-SLi Motherboard
NVidia 7300GS 256MB Graphics
300GB Samsung SATAII HDD
2GB Corsair DDR667 RAM (4x512MB)
Corsair 620W PSU
17in LCD Monitor
I'm having a strange screen corruption issue, whereby I get intermittent blue-ish lines appearing on the screen. At first I suspected fault graphics memory, so I changed the card. I then thought that the motherboard was at fault, so I had that swapped out. I've stress-tested the memory and CPU, and they don't seem to have a problem. I've changed the PSU and replaced the stock AMD cooler with a decent Zalman one. I've tried a different monitor, and I've even tried the system in a different room (on the same floor). Still the problem persists! It's not OS specific, as I have had the same problem in different operating systems. The problem is more noticeable in 32-bit colour than it is at 16-bit, but it's still there.
The only thing I can think of is that there is some sort of 50Hz hum that is causing it. Our electricity is prone to be a bit dodgy at times. I've realised that my surge protector is getting a bit old now (about 4 or 5 years), so could this be giving up the ghost and be letting in spurious surges? Should I go for something better like a UPS?
I've built and fixed a lot of PCs in my time, so I'm usually pretty good at diagnosing problems. This one has me completely foxed though. Any ideas?
Posted on: 21 September 2006 by BigH47
Any chance of trying it at a different property? It sounds like it is similar to microphony lines on a TV set when the built in speakers are too loud.
Posted on: 21 September 2006 by mharttpalmer
Yes, I'll chat up my neighbour tonight. I built her PC for her, and she's already brought her monitor round to my house, so I'm sure she won't mind me going round for a few minutes to see if the problem occurs there too. Trouble is I'll need to take up a weighlifting class this afternoon - my case is VERY heavy (decent Antec case with sound deadening inside it!)
Thanks for the suggestion. I'll let you know how it goes once I've got the strength to type again...
Posted on: 21 September 2006 by Phil Cork
Sounds like you've exhausted everything else - it's not the PC, and it's not the monitor, which leaves RF/mains interference...
Do you have a bad earth in the house? Do your lights flicker?
Phil
Posted on: 21 September 2006 by mharttpalmer
Yes, the lights flicker quite often, and the area has been prone to power cuts occasionally. Maybe it is time to invest in a UPS which would help to even out surges?
Posted on: 21 September 2006 by Phil Cork
your power supply company should investigate this free of charge. When I worked with London Electricity over a summer (during Uni) they had a piece of equipment called a Drannetz (sp?), which checked the supply for spikes, harmonics, interruptions etc.
Worth giving them a call.
Phil
Posted on: 21 September 2006 by SteveGa
quote:
Originally posted by mharttpalmer:
Yes, the lights flicker quite often, and the area has been prone to power cuts occasionally. Maybe it is time to invest in a UPS which would help to even out surges?
For certain, especially if surges, spikes and cuts are regular. Just make sure you get one that can keep your pc and monitor up for a reasonable amount of time.
Steve
Posted on: 21 September 2006 by Phil Cork
Hmmmm i'm not sure a UPS is the only answer. They quite often use square waves etc rather than nice clean sinewaves for the AC power they generate, and as a consequence, can introduce quite a bit of noise on the supply...
Phil
Posted on: 21 September 2006 by Rasher
You might want to check
this out in case it helps. You never know.
Posted on: 21 September 2006 by SteveGa
quote:
Originally posted by Phil Cork:
Hmmmm i'm not sure a UPS is the only answer. They quite often use square waves etc rather than nice clean sinewaves for the AC power they generate, and as a consequence, can introduce quite a bit of noise on the supply...
Phil
Yeah need to word things a bit better - UPS ideal for power outages when you are working. Doubt if they'll do much for Blue Lines. Intersting thing those Blue Lines...
Posted on: 21 September 2006 by mharttpalmer
Well, I've tried my PC in my neighbour's house. Same problem. Now I'm totally baffled. . .
Mark
Posted on: 21 September 2006 by Phil Cork
If it's a mains or RF issue, it would be likely to affect the neighbours house also. However, why it doesn't affect their PC is an unknown. Check the earth on your computer/case/power supply/cable/socket!
If you have a bad earth you're more susceptible to interference.
Phil
Posted on: 22 September 2006 by SteveGa
Some Friday afternoon thoughts from a couple of people I mentioned this to:
Can you think what changed/was introduced before the problem started "several weeks ago".
When you say different OS do you mean Windows, Linux and Mac or 2k and XP?
Does the effect occur on a minimal system: Mouse, keyboard, PC box, Monitor. Nothing else connected, in particular no audio products.
Is the LCD running at it's native resolution? Is it being run higher maybe?
Also what frame rate is it being run at? 60Hz or higher
I presume the video connection is a DVI not analogue? Can you try another cable?
A long shot but is there any chance that you have been tweaking clocks and memory settings in the BIOS. If so returning to defaults might help.
Also when do the bars appear? Does it coincide with disk activity or CD spinning up
Steve
Posted on: 25 September 2006 by mharttpalmer
quote:
Can you think what changed/was introduced before the problem started "several weeks ago".
I upgraded the system, upgrading the processor, motherboard,memory and hard disk. I did a clean install, and I believe the problem started from the outset.
quote:
When you say different OS do you mean Windows, Linux and Mac or 2k and XP?
I've tried Window XP Pro, Vista Ultimate RC1 (both 32 and 64-bit).
quote:
Does the effect occur on a minimal system: Mouse, keyboard, PC box, Monitor. Nothing else connected, in particular no audio products.
Yes, the effect still occurs on a minimal system.
quote:
Is the LCD running at it's native resolution? Is it being run higher maybe?
Also what frame rate is it being run at? 60Hz or higher
It's running at its native resolution of 60Hz.
quote:
I presume the video connection is a DVI not analogue? Can you try another cable?
I've got both analogue and DVI connections on my monitor. I've tried both, with the same results. I've also tried different cables.
quote:
A long shot but is there any chance that you have been tweaking clocks and memory settings in the BIOS. If so returning to defaults might help.
I've done no tweaking of the BIOS. I'm using the latest BIOS with default settings.
quote:
Also when do the bars appear? Does it coincide with disk activity or CD spinning up
It seems to coincide with disk activity. For example, Adobe Audition 1.5's main wave display window has a black background. If I use the transport controls to rewind/fast-forward through a recording, the corruption gets worse as there's more disk activity going on.
Many thanks for giving such a detailed reply Steve.
Regards
Mark
Posted on: 25 September 2006 by SteveGa
Hi Mark
Progress then!! OK looks as though we can discount any software being the cause.
Silly question number 5044 - when using the DVI cable it is working in Digital mode and not analogue?
In theory the video should be immune to these artefacts under a digital connection.
Also I guess the LCD mains and PC mains are in adjacent sockets probably in the line conditioner together? Rather than one in the conditioner and one a trailing lead to the other side of the room? Try this see if it makes any difference.
Anyway back to the trail just a little test to confirm the suspect.
If you change the desktop background colour to best display the fault (I guess black?) and then run a scandisk test. Make sure you don't enable "fix file system errors" or "bad sectors" otherwise it will schedule it on boot up. This is a low processor utilisation test but thrashes the hard disc. You will then have time to match the disc activity LED to video noise this should confirm the culprit - then we can solve the problem!
Steve & SteveB
Posted on: 25 September 2006 by mharttpalmer
Hi Steve,
I really appreciate you taking the time to help on this one! I doubt that I'll be able to do any more diagnosing/testing before Thursday week, as I'm off to Greece the day after tomorrow (where I can forget about the whole saga!) I'll report back then.
Cheers
Mark
