Only way to get that high of temp idle with a decent heatsink is if it is not sitting flush on the CPU core. Verify that the heatsink is oriented the proper way and that the clip is applying pressure directly above the center of the core. (The clip is offset, so if it is backwards, the pressure will not be centered above the core.) If you are using a shim, it could keep the heatsink from properly contacting the CPU core if it is slightly out of tolerance or bent as little as 0.003" (This small bend would be undetectable unless you laid the shim on a flat piece of glass.)
Arctic Silver II will not bridge an excessive gap like a thick thermal pad will so it is imperative that the heatsink be installed properly. There are several threads like this on other forums and after multiple Arctic Silver bashing posts, the originators all eventually discovered that the heatsink was backwards, or the clip was backwards, or the CPU was not fully seated in the socket, or there was an eyelash hair between the CPU and the heatsink, or the shim was bent, or the shim was defective.
Nevin House
Arctic Silver, Inc.