OK so there's a number of things we need to look at this point.

First off, something that we might start with is getting you to install Speedfan. When you open it up, there's a tab called S.M.A.R.T., open that up, and select your HDD from the dropdown list. Take a screenshot and post that.

Second, and I'm getting the sneaking suspicion that this might be the real culprit, is your ATA controller on your mobo might be going south. There really isn't any way to test this aside from swapping out with a new known good mobo and running for some time to check for stability.

Third, there's a potential it could be other components. RAM and PSU are often tricky to troubleshoot and can create problems that are hard to trace back to them. Heat is another problem, unless you're 100% sure of the ranges of temps that your equipment is experiencing then it's not wise to eliminate that, that's not something one can get from "feel" or "intuition."

Start with that and we'll work from there.