Temps should NOT get that hot with these processors. Somewhere between 120 and 150 degrees F would be more acceptable. I'd double-check the CPU fan to make sure it was 1) blowing air down onto the processor and 2) actually spinning. Is the heatsink on backwards (as in not physically touching the actual processor core)? I'd also re-check the Arctic Silver application (sometimes too much can trap the heat in the core). Very small amount of heatsink compound is required (very thin layer of compound covering the core). All the compound does is fill in any imperfections on the bottom of the heatsink so heat can transfer better. If there is a lot of compound "spilling over" the edges of the core, too much has been applied.