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I have a Dell Dimension 420 that has suddenly developed what I am calling a "blurry" screen.

  1. First: Screen went all pixelated:

    pixellated screen

    Mouse would no longer move (laser still on), and keyboard CAPS lock would not toggle or illuminate. Windows Side Show on the case LCD ceased responding (said something about could not communicate with Windows). No blue screen. Had to power cycle.

  2. Second: Above symptoms repeat after ~5 minutes of normal use after booting.

    desktop after minutes of use

  3. Now: Seeing blurries even when in the BIOS, Windows repair screens, and Windows logon.

    bios screen

    windows repair screen

    windows logon screen

What I have tried:

  • Replacing monitor (with a spare)
  • Replacing all monitor cables
  • Sadly, I have no on-board video card (or spares) to test with

I almost assume it is the video card (since the problem is in BIOS too) except when it initially also affected the keyboard as well.

Misc machine specs:

  • 32-bit Windows Vista Home
  • 3 GB RAM
  • E6820 processor
  • Video card - standalone, DELL G92 HMGA16
share|improve this question
If the screen is blurry in the BIOS screen then it has nothing to do with Windows Vista. Probably a bad monitor or video card as you have guessed. – user89061 Jul 29 '11 at 13:28
It is almost certainly your video card. There is an outside chance it is your motherboard, but doubtful. As the others said, the blurriness on boot, before Windows, really narrows it down to MB, Video card, or monitor, and you ruled out monitor. – KCotreau Jul 29 '11 at 20:40
up vote 1 down vote accepted

The system locking up the first time you saw the failure would tend to indicate your system is overheating, and that the normal hardware protection for such a situation has not worked as expected - fans have not ramped up their speed, and the CPU and GPU may not have dropped their operating speeds to allow themselves to cool.

If your system BIOS has a health-monitoring screen, check your recorded temperatures - if they are high, you have a definite overheating problem.

Verify that all fans are running, that air is flowing correctly through your system, and that your air intakes are clear of contamination. Verify that all heat sinks are also clear of contamination - if necessary clean with a can of air-duster.

If everything is clean, airflow is good and all fans are running, then I would suspect a faulty video card - but not until ruling out temperature and contamination as a source of the problem.

share|improve this answer
Hi Mike, thanks for the great pointers! I will clean the chassis, run dell health checks, and cool the machine tonight. It has been unseasonably warm here in the northeast. – Chris Anton Jul 29 '11 at 16:31
Hi Mike, You were right, the video card was toast! I poped an older one in, and all was working correctly. Bought a new video card to replace the busted one, should be here shortly. Thanks again for the detailed help! – Chris Anton Aug 2 '11 at 15:12
Glad you found this helpful - and that it was just the video card rather than a motherboard failure :) – Mike Insch Aug 2 '11 at 15:18

Blurry screens, even in BIOS, would not seem to me to indicate overheating. Especially if I'm reading your question correctly. Use the following test to determine if this is the case:

Leave the computer off for at least several hours to make sure all the components have cooled down sufficiently. Then turn it on. If the BIOS screens are blurry at this point the problem, while it may have been caused initially by overheating, is no longer the direct fault of overheating. Now it's damaged or faulty hardware.

Now the question is: do you have a discrete graphics card, or are you using onboard/embedded graphics? (As in, is the graphics card a separate device plugged into the mainboard and the connector you plug your screen into on the computer is perpendicular to most of the rest of the connectors and projecting through a slot in the case, or is the graphics connector grouped in with all the other USB and network and other ports?)

The screen is probably the obvious choice for swapping first. It's cheaper, and you can probably use a spare or borrow one from a friend briefly.

If the issues still occur on a different screen then you need to check your video card. If you have a separate (discrete) graphics card, get another comparable one and swap them out. If the graphics are embedded, you may still be able to purchase a cheap graphics card just to test. If it works, hey you fixed your system for the price of a cheap graphics card. If it doesn't, you've gotta replace the system, most likely. It'll probably be cheaper to replace than to repair, unless you have a warranty still.

share|improve this answer
Hi music, The graphics card is standalone (not onboard). It is most likely PCIe, but I haven't cracked the case to see. I have swapped the monitor and all affiliated cables with no success. Will work on a replacement video card. Thanks for the help! – Chris Anton Jul 29 '11 at 16:34
Actually, these are precisely the symptoms of GPU underfill cracking. This actually gets better when the GPU is hot because it expands and fills the cracks. When the GPU is cold, the cracks prevent the GPU bumps from making contact with the board. – David Schwartz Feb 8 '12 at 7:08

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