The hotter the case, the hotter the CPU.
You COULD try to re-do the ASIII part, but if its 45C inside your case the CPU is likely to reach 50C under stress. Couldn't hurt to try though.
Also, is the heat sink flat and completely level? Are there any machining spots on it? You could lap it if it is neccesary.
On a personal note, wouldn't you much rather be running Folding@home than Seti@home? We have a good team of brave folders that could use your help! 