So I returned my MacBook yesterday... I ran the python script outlined in the Ars review and watched the CPU temp/speed with the CoreDuoTemp application. I have a 1.83 model but during the test I couldn't get the thing to actually run at that speed for more than few seconds. The first test I did was on battery power only. I set the energy saving preferences to best performance hoping it would run at 1.83 while the CPU was pegged. It did not. The CPU oscillated between 1500 and 1667 with temps from the low 80s to low 90s. So I tested it plugged in. I made sure their was no airflow restriction, ambient temperature was 75F. I let the thing run for three hours with the CPU pegged. The CPU temp was in the upper 80s and the speed was 1667 with an occasional drop to 1500. Now is it just me or does this seem like a problem? Shouldn't my laptop run at the advertised speed? Is it unreasonable to assume a 1.83Ghz computer would be capable of running at 1.83Ghz for a sustained period? I took the thing to an Apple Store in Dallas. I explained to the "Genius" what was happening. I told him about the python script and showed him the CoreDuoTemp application. The first thing he said was, "Well, we can't trust what this application is telling us since it's not designed by Apple." Fine, I said. Load up your Apple Approved CPU Utility and I'll demonstrate what's happening. He didn't have one. I explained the problem again. I told him my MacBook wouldn't run at the advertised speed, that it throttled the CPU because it got too hot. He explained to me this was "normal behavior", that computers throttle down their CPUs sometimes when they are under 100% load. I said I could understand this if it was set to preserve battery power but in this case it happened when it was plugged in. The "Genius" said depending on the application requesting CPU resources it may scale the CPU down anyway, even if it's plugged in. So I asked him what would happen if I was doing a video conversion or encoding an audio file. He said it would probably behave the same way. What? I asked him what the point was of purchasing a 1.83Ghz computer if the processor would never run at that speed. I asked if it was unreasonable to expect my PC to run at the maximum rate when doing audio encoding. He suggested we perform a test on a floor model and see what happened. He downloaded the CoreDuoTemp app on a 2.0Ghz MB, started up three or four Chess games and made the computer play itself. The CPU went to 100%, the temperature shot up to 91C and the processor throttled down to 1667. BINGO! There's my problem! This MacBook had the same issue. "Normal behavior" I was told. I argued with this guy FOR AN HOUR until he finally said I could exchange my 1.83 for a new one or return the one I purchased. He even said he'd try to get the manager to waive the restocking fee. So the "Genius" left for a few minutes and was replaced by "Genius Manager". "Genius Manager" said he heard I was having a "special problem" and that he was here to help. I went through the entire explanation again with this guy. "Normal behavior" he said, that's what happens when the CPU goes to 100%. The CPUs have to throttle to keep the machine cool. He said I did not have a heat issue, that a real heat issue would be like something he'd seen before where the case of a MacBook Pro actually warped (Apple replaced this laptop). He then said that if I was doing CPU intensive work I was probably in the "wrong machine" and should consider upgrading to a MacBook Pro. What? Are you kidding me? Aren't the specs of the MacBook nearly identical to the MacBook Pro? He mumbled something about "bus speed". After talking to "Genius Manager" for 45 minutes he said I could swap my 1.83 for a new one and that he'd waive the restocking fee. Of course every time I hear the words "restocking fee" I get more agitated. I told him I was thinking about just returning the MacBook in exchange for my cash and waiting to buy a MB when Apple made a reliable product. "Restocking fee" he said! He wouldn't waive it if I just wanted to return it. To make a long story short I exchanged my 1.83 for a new one. The new one actually runs at 1.83. It runs at 1.83 under 100% CPU load while running on the battery and while plugged in. My new MacBook RUNS AT THE ADVERTISED SPEED. Now correct me if I'm wrong but aren't their laws against making false claims in advertising? If this issue is widespread and Apple keeps up this charade they are going to find themselves with another class action lawsuit. My suspicion is that the initial run of MacBooks (I bought mine the day after they came out) had some production problems. My new one does get hot but it's not as bad as the one I returned. The manager replaced my MacBook because he couldn't win the argument. But how many people who aren't technically competent have been turned away that have genuine heat problems? How many people are lead to believe this is "normal behavior"? My experience with the Apple Store was poor. Despite the fact that the people were polite there is no excuse for what I had to go through. I was there for TWO HOURS. Has anyone else had a similar experience?