Black flickering areas in backgrounds of games

Hi,

I'm getting black flickering areas in backgrounds of games and am worried its a hardware problem.

I recently purchased an evga factory overclocked nvidia gtx 260 216 to go on my system and started noticing these flashing areas appearing in last few weeks. I changed drivers but it made no difference - currently using 182.06 forceware . It does not actually stop the game from working, games run fine, but these occassional flashes and flickers can be distracting. They might happen once every 10 seconds. It does not seem to follow a regualr pattern.

My system specs are:

vista ultimate 32bit
asus p5qpro mb
intel core 2 duo 8200 2.67mhz
4 x 1gig ocz reaper pc8500 memory
evga gtx 260 216 896mb superclocked
creative xfi gamer soundcard

I wondered if anyone else had come across this? Did a search but came across nothing though a poster did alude to memory problems on a card if this happens. It does seem that textures are not being filled quick enough. in rise of the argonauts there is also a kind of checkerboard effect where the texture should be, for a split second. Anybody come across this?