Netbook screen display is garbled (has black/white & horizontal line patterns, screen freezes, and/or wrong display position)

Question

Upon powering my netbook on, its screen turns into a garbled display (has black/white patterns, horizontal line patterns, screen freezes and/or wrong display position). This distortion happens even at BIOS startup, continuing to Windows startup. Occasionally, the issue starts around 3 minutes after the Windows desktop appears.

Pictures of the monitor (click on image to enlarge):

More pictures at: http://imgur.com/a/ArME1

Details:

• This happens even in safe mode (the last picture above is of the netbook screen in safe mode).
• I connected the netbook to an external monitor (through VGA) and the display in the external monitor shows up just fine. I have been able to use the netbook without any issues with an external monitor.
• Aside from the monitor, the netbook still works (I can shut it down with keyboard shortcuts) and the files that it has shared through LAN can be accessed fine. The torrent client's web interface on the netbook can also still be accessed on another computer.
• The issue sometimes happens even at BIOS startup.
• The variations of the distortion will sometimes change randomly.
• Occasionally, the non-distorted screen display will simply freeze.
• The netbook didn't fall in the ground or get hit by an object.
• The netbook is mostly used as a torrent seeder and downloader. Its lid is opened and closed around 2 times a day only, but the netbook is powered on almost 24/7 (its lid is closed most of the time). It is mostly accessed through another computer through LAN and is not often used directly.
• The netbook was bought around 2 years ago.

What are the possible causes of this? Any possible fixes or methods of repair I can look into? The netbook is now out of warranty.

Netbook details:

• Model: Samsung NP-N150
• OS: Windows 7 Starter
• Graphics Chip: Intel GMA3150
• Monitor: Screen Size 10.1", LED Backlit
• Other specs here: http://www.samsung.com/us/computer/laptops/NP-N150-JA01US-specs

Solution

Putting a live linux distribution on a USB stick would let you test hardware vs software easily. Seeing what happens if you sit at the BIOS screen like Bobby suggested isn't a bad idea; but a pure textmode display will put significantly less load on the GPU than GUI desktop will.

Since the problem doesn't occur immediately on powerup, the only cause that seems likely to me is overheating. Have you verified that the fan still spins. Taking the bottom off and blowing out any accumulated dust should help here.

CoreTemp will let you monitor the CPU temperature; if it's really high the odds are your GPU is also overheating since the GPU and CPU are integrated but I'm not aware of anything to read the GPU temperature directly.

Comments

[Jjames]

Verify: Does this also happen in BIOS? Temperature of GPU? Goes away after reboot for next few minutes?

[galacticninja]

@Bobby Yes. This has also happened at BIOS startup (just found that out). It sometimes goes away after a reboot, sometimes it doesn't. I also connected the netbook to an external monitor (through VGA) and the display in the external monitor shows up just fine. I'll see what I can do to check the GPU temperature.

[galacticninja]

"Since the problem doesn't occur immediately on powerup, the only cause that seems likely to me is overheating. Have you verified that the fan still spins." I just found out that this also happens at BIOS startup. To further troubleshoot this, I connected the netbook to an external monitor (through VGA) and the display in the external monitor shows up just fine. I can't seem to find a fan for this netbook (it probably doesn't have one). I still cleaned its exhaust vents at the bottom.

[galacticninja]

I connected the netbook to an external monitor (through VGA) and the display in the external monitor shows up just fine. I have been able to use the netbook without any issues with an external monitor.

[galacticninja]

Not sure if this is a normal temperature for this CPU, but here's a screenshot of CoreTemp, ~3 minutes after the Windows desktop appears: imgur.com/yJbBq (Min: 57°C, Max: 61°C, Tj. Max: 100°C). Screenshot from HWMonitor, ~30 minutes after the Windows desktop appears (not sure which is the GPU temperature): imgur.com/XCsiL

[Dan Is Fiddling By Firelight]

Those numbers look normal. Your netbook does have a fan though; vent on the right side. This teardown guide is in Italian; but the pictures are universal: netbookitalia.it/…