It seems that heat is your problem, so let's attack it
My first recomendation would be improve airflow. Check around the net about rounding cables and case airflow. What is currently your ambient temperature? And the temp in your case? One easy way to see how much you need better airflow is the following:
a) Run your computer at full load (with programs like Prime95 or similar). Write three temps: CPU, mobo and room. Mobo and room shouldn't differ a lot.
b) Now open the case and make the same process. Room hasn't chance but mobo and CPU have gone up. The higher difference, the more you need to improve airflow. Note: don't expect to reach the same temps, this can be difficult and expensive.
If you want to invest low money and obtain good improvement, try to install in your case one fan in the bottom front blowing in and another one in the upper back blowing out.
Finally, I made some research about your HSF. It doesn't seem the best (also Orbs are not known for great cooling, but for good looking). Here you have a review that compare some HSF. Regreatebly, yours is the worst:
http://www.extremeoverclocking.com/reviews/cooling/HSR2_5.html
But changing the HSF would be the second step, at least IMO. Probably just with better airflow your computer can run ok. In case you are interested in purchase a new one, recently THG made a comparison:
http://www6.tomshardware.com/cpu/02q3/020916/index.html
Or you can search/ask in the forums. Lot of info.
Hope this helps!
DIY: read, buy, test, learn, reward yourself!