Yes, both will do 4K although the 300MHz one is restricted to 8-bit at 4K60. Because standards are so complicated and the permutations are enormous, you often see incompatibilities - there was an example a couple of years back with LG - can't remember the exact details. but everyone on the forum with the issue swore blind it was Zidoo at fault and when the Zidoo devs bought an LG to test, it turned out to be crap programming by the LG guys and eventually a firmware fix was put in place - but with a big lumbering beast like LG, it took a while. In the meantime Zidoo gets a bad name for no good reason. It's easy for people to say "but my XYZ box works" but it's rarely a like for like test.