jelleHNL wrote:But like I said it does not happen in the same places all the time nor do the files seem corrupt.
Like I said, I've seen it both ways. Sometimes this sort of thing is corruption in the clips, sometimes it's just software misbehaving. The resulting image is highly suggestive of wavelet decompression going wrong; GPU artifacts aren't likely to have that type of structure. Observationally, I've seen that sort of effect with Red footage on known-good hardware, and meanwhile I never saw anything that severe on with our faulty Mac Pro, across many hours of test renders, with non-Red footage.
jelleHNL wrote:I had the same thing happening on SD and HD footage (all sorts of flavours) before OSX 10.9.4. The update cured a lot of errors on my system but seemingly not everything. The fact that I had errors all over the place from the start seemed to indicate faulty hardware after reading this thread. Especially when reading that the problems of others were cured after a replacement unit.. By the way, these screens were the most severe ones, most of them are the blue/green/pink horizontal lines.
If you also see artifacts similar to the 1 or 2 line horizontal lines, it is, of course, easily possible you've got the Mac Pro GPU issue being discussed in this thread
and you're running into Red workflow flakiness. Neither of these seems to be especially rare, so encountering both the same machine isn't all that implausible.