That is artifact, it is usually the result of overheating. So I would go ahead and turn the fan speed to max and see if it goes away. You may need to clean the card and is the first thing I would and normally do. It may look clean till you take a look under the shroud to find that it is clogged with dust.
If there is still some dust even if it is a thin film it is not clean. Replace the old stock compound since it usually goes bad after a few months use on most cards including matrox and ati. So here is my little question for you is the issue showing up in 2D as well? Second question what is the model of your psu (just saying the wattage doesn't pass)?
The psu may be part of them problem since this is one of those generic crap units, generic pc hardware isn't near the same quality as some repeatable brands such as antec or enermax. If the problems don't go away after cleaning the card and getting the temps below 70c under full load then start by getting a new psu that has better 12v wattage as well a higher quality build. If the problem remains but the system as a whole gets more stable then your heading in the right direction. Operating components on high or low voltage can damage power stages (mosfets, diodes, exct). 12v give or take .3v is good enough for just about any system depending on some factors.
If it is not overheating, these are the symptoms of a dying GPU. Could be GPU memory, could be the GPU processor, but if you are getting these and it is 85c or less, you are going to have to invest in a new GPU. MIGHT be the PSU underpowering the card, maybe. This does not look like that is the problem, but it is always a possibility.