RE: DVR (Scientific American 8240HDC) Pixeling and Freezing

Well I could be wrong but I think Scientific Atlantic is a old old wooden ship that was used in the Civil War era.  

As for the OP, I think it would be useful to know what the actual signal levels are at that outlet. The link below shows how to get into the diagnostics. Once in, I think you go to RF Network, but I don't have a box of that type myself, so I am not sure. 

http://www.dslreports.com/faq/11880

Or you could hook a modem to the outlet and use the 192.168.100.1, but that won't be as precise, because it will give you reading of a different frequency then what cable uses. Probably similar..but still different. 

It sounds like to me that the first box died, probably from overheating. Now the new box may also be having heat problems but also a DVR splits the signal between two tuners, so the signal is naturally weaker. Weak signal usually causes tiling. But tiling doesn't happen right away, because like a CD player there is a certain amount of buffer. That buffer is used up by the DVR cache though, and thats why rebooting the box alot of time is a temporary fix. In the end you won't really know until you get some hard data. Some tech's have special meters that can measure the signal but they are expensive, so not all Technicians have them, at least in my experience.