+1 on the heat issues. Clean the dust out of the card, and check to make sure the fan is working correctly. A card that is a couple years old it is not unusual at all for the fan to go belly up on you. Since the 1950 pro exhausts air into the case, check your case and PSU fans as well to be sure of good case ventilation.
for whatever it is worth,,sometimes when a psu is on it's last legs,,depending upon system configuration,,you will get video artifacts,although what I usually see is a general slowing down of the system while in operation,the variable is due to ,,1, how a system is tuned and,, 2,how much power it draws and,,3 ,the age/output of the psu,,so besides the above suggestions you might try another psu,,generally speaking video cards rarely produce artifacts and, when they do well,,see above..
At first, i thought it could never be a heat issue cause i stuck a pretty strong vacuum cleaner to it and sucked out what i thought to be all the dust.
Then you guys sounded pretty sure it was heat, so i took a twist tie and poked around the small crevaces in the fan grills, cause i could not see the grill good enough due to the dark blue tint of the cover.
Low and behold, chunks of dust balls came out, and i took a hair dryer, and set it to cold, and blew it all out.
Im pretty disgusted at how sapphire made the case that covers the heatsink very hard to take out, to the point where i had to use a hair dryer to remove dust.
well anyways, artifacts are back to zero, thanks to you guys.