Here's a good news update!

After adding some thermal paste and allowing it to cure, I've actually achieved speeds just over the rated 5ghs. So stoked! 
This is good news for anyone who has the same issue.

Now if only I could add a few more chips to it and run it off the same PSU.

http://eligius.st/~wizkid057/newstats/userstats.php/1JxGGxnttFdw3dK6FE1dohYmrXVjTFcQc4