Finding a new heat sink for a dell dimension 9200c???

[LegendJared]

I really need help finding a better heat sink for this case and I don't know of any cases compatible with this mobo my cpu does get hot and and gets to upper 40-lower 50s while just useing google chrome I would really apreciate any feed back you can give me also I have notice when I run prime95 to see how my cooling is it gets up to 85c in just 4 mins and takes almost 15mins to go back down to the 50s range

 

[LegendJared]

here pictures of my case and board http://imageshack.com/a/img839/7024/6x26.jpg
http://imageshack.com/a/img843/8315/r49w6.jpg