Sorry to comment on such an old post, but I can provide an e-mail direct from Thermalright stating the convex base is intentional. I purchased a TRUE (1366) last week, and there is definitely a slight bulge which appears to come from one of the center heat pipes on one side. Thermalright responded promptly to my e-mail today, telling me it was designed that way... They say the CPU is slightly concave, though I can't imagine that the curvature of the CPU could exactly match the curvature of the heatsink, since it doesn't appear to be a uniform bulge (I haven't tried installing it yet)...