These symptoms tell me that you have a component somewhere in the system that has partially failed and does not work properly until it has been heated up substantially. Eventually, it will fail altogether. In order of priority (only educated guesswork on my part, I have to admit), I would look at these components:
- Failure in Graphics card. Remove and test system using internal graphics. [Aside: this is unlikely, but getting the graphics card out of the system is something to do anyway, so do it first - and keep it out for all subsequent testing. Note that, if this alleviates issue, there is still a possibility that the real problem is a component in the PSU.]
- Failure in Memory DIMM. Remove all DIMMs and then test them one at a time (placed in Channel A DIMM 1 socket; the blue slot closest to CPU), If the problem is not present with a particular DIMM, then you know that one of the other DIMMs is likely the culprit.
- Failure in PSU component. Test with another PSU.
- Failure in motherboard. IF you are inside your 3-year warranty period, time to call Intel Customer Support regarding a replacement.
Hope this help,