The culprit is faulty ram. You can run memtest to stress the ram. If memtest reports the ram is faulty, ram is bad. However Memtest is not a perfect tool to test the memory as some faulty ram can pass memtest.
Suggestion
1. Check the temperature of the CPU and make sure that it is not overheat (ie temperature < 60C)
2. Reseat the memory stick to another memory slot
3. Downclock the ram
4. Clean the dust inside the computer case
5. Make sure that the ram is compatible to the motherboard
If it still crashes, diagnostic which memory stick is faulty
1. Take out one memory stick. If windows does not crash, the removed memory stick is faulty.
2. If you have only one memory stick, replace the ram
