Graphic Glitch

November 11, 2012 11:45 PM

Can you figure out this weird PC graphics glitch?

My gaming laptop has developed a seriously messed up graphical glitch. It manifests in a couple of ways.

1. There are sometimes symmetrical blocks of lightly colored pixels scattered all around the screen. On a black background, they're green, and on white they're light red. It rarely makes watching streaming video kind of annoying, but nothing too serious.

2. The big one. Whenever I play almost any game with decent graphics, two things tend to happen: On some games, polygons don't fit together right, so you can often see right through the seems, especially on closeups like with faces. On almost EVERY game, character models, buildings, plants, everything in the environment sprout these enormous random graphical spikes that extend in all directions and make everything look like it comes from a planet of crazy cactus creatures.

I suspect that there's some kind of loose connection in there somewhere, but, this being a laptop, there's no simple way to get inside and check. It's a Gateway FX running Windows Vista with 4 GB of RAM and a 1 GB Nvidia 9800 GT video card. I know it's not the most high-end gaming laptop on the market, but for two years, it ran everything I threw at it like a champ. Now, those glitches show up in games I used to have no problems with and in any new games I try.

I'm fairly certain at this point that the lappy is going to be resigned to internet surfing, video watching and routine tasks. I'm seriously considering getting a console for my future gaming needs, but I thought I'd consult the hive mind before making a final decision.

posted by ronofthedead to computers & internet (6 answers total)

Sounds like somehow your video card is coming up with the wrong numbers for its geometry maths. If the drivers are up to date, probably that means the video card chip or RAM is damaged in some way.
posted by aubilenon at 12:10 AM on November 12, 2012 [1 favorite]

Sounds like overheating to me, laptops clog with dust quite easily.

There's a million programs that can monitor GPU temps so you can check, e.g. GPU-Z. Everybody on the net disagrees what "safe" temperatures are - I'm usually worried if they get anywhere near 90 degC.

If you do need to clean it, find a disassembly guide online first. I don't recommend actually removing the heatsink from the chip unless you're used to applying thermal paste yourself - just clean all the dust out from the finned radiator on the end of the heat pipe and decrud the fan blades. Don't use canned air!
posted by samj at 1:17 AM on November 12, 2012

Unless the blocks are always appearing at the same location then it's likely a problem with heat and the graphics chip. But if they're always showing up at the same location then it could possibly be a problem with the screen. As has been suggested, a thorough cleaning of the inside would be a good idea. And since the effort to get in there to clean it involves removing the case, it would also likely be as good a time as any to re-seat any heatsinks that might be present.

Search for your specific model number online and see if anyone has detailed the process of getting it apart. Be specific, as what works for one model of a laptop generally does not work for others. Small variations based on some accessories can be allowed for, but not if the variation includes the graphic processor setup. The addition of a bluetooth or wireless module doesn't usually affect the whole machine, but the motherboard for one with a higher-end graphics processor usually does.

But start by testing the situation when the laptop is fully cooled-down. Leave it at least overnight and then test for how a known problem appears. If the problem isn't there when the machine is first running then it's very likely a heat-related problem. This isn't to say that a defective heatsink connection wouldn't immediately cause overheating, as that's certainly possible, but less likely.

So start by searching for what it takes to get that one apart and decide if you're able to do it. Otherwise consider having a local shop or technically inclined friend do it for you.
posted by wkearney99 at 5:20 AM on November 12, 2012

Do these issues manifest 10 minutes or so from bootup? Or are they there right away? If it's the latter, then if it is damage, it's likely already done. I've seen this anomaly over the past 15 years on all kinds of video cards; it's normally video RAM and its ability to sync up with the internal clock. (back in the day there used to be settings in the BIOS to adjust timing delays which could prolong the life of the card a little).

However, I think you should check your BIOS anyway and make sure you're not inadvertently overclocking your system. Also make sure you're not OC'ing your video card within the driver's properties. There may be additional tweaks you can do through the nvidia panel as well. (Make sure you're on the most up to date driver for the 9800 by downloading it from Nvidia's web)
posted by samsara at 5:37 AM on November 12, 2012

This also sounds like overheating to me. It could also be video ram. I believe there are testers for video ram, but I can't think of any off the top of my head.

My computer also has this problem, but with video. When playing a video that is large, it will drop framerate until it's down to nothing. Or it will not render properly, with digital "fuzziness". It's worse when my heatsink is clogged with dust.

So check for dust, and then investigate your heatsink. If you have the skills to dig into the machine. If not, you might bring it to a place and suggest they make sure the heatsink is working. Laptops have heatsinks with heatpipes, which depend on a fluid to work. It is rare, but that fluid can evaporate out and make the heatsink not work very well at all.

One way to tell that bad heat flow is a problem is if the fan is spinning fast, but the air coming out isn't very hot.

It also couldn't hurt to test your regular ram by creating a bootable CD of memtest86+. They have downloadable ISO files. You then boot the machine with it and let it run. If it gets through the first 4 passes without any red, you are probably OK. If you get any red, your RAM is definitely bad.
posted by gjc at 7:04 AM on November 12, 2012

Another bit of information about graphics cards- they (or their drivers, I guess) employ algorithms that are "fuzzy" in nature. They aim to get the graphics as correct as possible for each frame. But if they can't they skip it and move on. That's why you can get these weird polygons and cubes of bad rendering.
posted by gjc at 7:06 AM on November 12, 2012