I was having that problem 5 boxing. After tring a few times, the only thing that I found that fixed it (for me) was adding a 5th fan and having it blow directly across the video card. I had 4 fans running at that time in my system so I never thought it could be my video card runing hot. My video card has an on board fan so it was the last thing I looked at. Since I added that fan I have 5 boxed with my main monitor set on ultra and my second monitor, the 4 alts, set on good. No problems since.