Do you have integrated graphics? If so, you could take out the graphics card and run on that to see if the issues still happen. If they do, then return your graphics card for a replacement (although you probably voided the warranty by OCing regardless of whether that caused it).
Lesson: If you want an overclocked graphics card then buy it overclocked at retail or buy a more expensive card. And also you should have spent less money on the CPU and more on the graphics card. Your games would run better if you had.







