I think a little bit more information is in order: what exactly happens when it freezes and generally what are you doing?
Just stabbing in the dark because of a general lack of information, but I'd guess a heat problem. Can you give some more details about the cooling you're using and the case + ambient temperatures + some component temperatures (I use "speedfan" for temperatures if you don't already have something in mind)
I don't have to do a complex thing (rendering or...) sometimes I open a program and it freezes and sometimes if I am working on a project it also freezes it don't happens all the time but each 2-3 days it happens once or twice.
I use "Intel desktop manager" to monitor the temperatures the CPU's temp is normal the ambient temp if rendering is about 42 43 deg C sometimes higher but never enters thr Red zone...
I dont think it's a heat problem because all the temp are normal
Please check this link to see the case: