The Matroska Media container is a very popular, open standard Multimedia container which is usually found as .MKV files. It is a very popular format in enthusiast circles and can be played directly in VLC or Windows Media Player with suitable codecs installed.
We played our High Definition MKV movie using the latest version of VLC Media Player.
Neither motherboard has a negative effect on CPU performance which could come about by applying an error to the i5 3570K's base clock setting.