PC freezes with screen showing mixed coloured lines

[makembill]

Hi all. I use a PC a lot but ask me a techie question about it and you may as well be speaking Martian, so please bear with me.

I have an intermittent problem whereby my PC freezes, and shows a screen of slightly off horizontal lines, sometimes black and white, sometimes like a candy strip. On one occasion the graphic on the screen was a vertical black line in the middle of the screen about a third of the height of the screen with a number of small horizontal lines crossing it, much like a railway line cut in half. The freeze occurs for no apparent reason. Sometimes I am tabbing between screens on the net (I am in the midst of a degree course and use the net for research while typing course notes and assignments), or just typing in word. I do tend to produce new documents in the 500gb Freecom external HD as opposed to the C drive but have experienced this problem in both. I have to reboot and obviously lose any unsaved work, which is usually only that previous half hour at most. On two occasions the freeze has been accompanied by a high pitched noise.

The problem sometimes doesn't occur for weeks than happens twice in an hour. It's been in the shop and they seem to be baffled as it hasn't occurred when they have it. Their best bet is a graphics card. One suggestion is that it’s due to their being too much RAM for the processor.

I have copied some tech info below so that many questions regarding what I am running may be answered. Sorry if it's over the top or missing important bits.

XP Home Edn 5.01.2600 Service Pack 3;
Mainboard : ASRock N68PV-GS
Chipset : (Family 10h) Athlon 64/Opteron/Sempron HyperTransport Technology Configuration
Processor : AMD Athlon X2 @ 2800 MHz
Physical Memory : 4096 MB (6 x 0 )
Video Card : Nvidia Corp GeForce 7050 PV / nForce 630a
Hard Disk : STM3250318AS (250 GB)
Hard Disk : SAMSUNG (500 GB)
Monitor Type : AZALEA - 17 inches
Video Card : Nvidia Corp GeForce 7050 PV / nForce 630a
DVD-Rom Drive : LITE-ON DVDRW SHW-1635S
DVD-Rom Drive : HL-DT-ST DVDRAM GH22NS50
Network Card : Nvidia Corp Nvidia Corp
DirectX : Version 9.0c (October 2007)

Over to you guys. Any advice would be gratefully received.

Regards, MakemBill

[gerbil]

Check that the heatsink on your northbridge is in good shape - that is where your IGP [integrated graphics, the 7050] is located. Could be a lockdown problem, or the paste letting go. Anyway, the lines come from the graphics processor failing in some way.
High pitched noise? Often comes from an overloaded power supply ; it gets dragged down from super-audio to audio frequencies. Caused by a short, or failed component that it is feeding. If the main PSU was overloaded to that extent you would see smoke.
If it's not a heatsinking problem, then it is off to the shop with it....
The CPU will address as much of the RAM as the OS will allow.
Are you running an LCD display..? they can do weird things to a picture, have plenty of onboard regulators, and i think that a failure there can freeze a PC if it's the right sort [one that affects the input circuitry]... always worth swapping out as a trial.
That's my two bob's worth, anyway. Good luck.

[makembill]

Thanks Gerbil.

You've given me something to consider and I'll look into your suggestions. I was concerned that it might be a graphics card issue but wasn't sure if that would affect the PC when such a variety of things were ongoing at the time the PC has frozen. By this I mean sometimes I am surfing across a couple or more websites, or using word, excel and maybe IE too or simply using word to write new documents. There doesn't seem to be any discernable pattern to the failures, although I imagine the graphics card is in use at all times the PC is running.
It may take a few days to come back and say what I've managed to get done, but I'll report back to the thread later.

Thanks for now,

Makembill

[gerbil]

Bill, you do not list a graphics card, so I have to assume that you are using the on-board graphics. That feature is built into the Northbridge, the large chip with a yellow? heatsink at one corner of the CPU. Simplest is to check its heatsinking is as it should be .
Programs you are running should not upset the graphics unit.... it would not struggle with web work, or manipulation of documents with excel etc., even if all are onscreen minimised at the one time. Not a card for gaming, but is an office workhorse/ home video player, very suited to what you are doing.
Don't ignore the VGA aspect.... monitor causing the freeze.