The gaming rig my hubby built for me is having very regular video lag even though neither the cpu (AMD Athlon II x4 635 2.9GHz) nor ram (8GB) are running over 40%. They're under 30% when playing WoW on ultra, but as soon as I start viewing, say, a youtube video at the same time, I get blips of vid lag every 1-2 seconds. Bringing WoW's settings down reduces the problem - at fair they go away completely. But at no time in this process did my cpu or ram break 40%. My vid card should be more than up to the job - ATI Radeon HD 5800 Series - and the drivers are updated. Any ideas what else the problem could be?
a weak cpu. if you have a 5870/5850 its to much for that amd cpu. which is pretty low down on the benchmark it has fairly similar performance to a q6700 and even that overclocked is no match for a 5870/5850.
you could try getting a better cpu cooler and overclocking the cpu to say 3.3ghz if it will go that far. it may ease off the bottleneck.