Tired of nearly burning my thighs with my Macbook Pro, I Googled around to find available notebook cooling methods, and came across something called undervolting, a way to lower the amount of heat a CPU emits. This appealed to me over other cooling options because: (1) I wouldnt have to buy a fanned cooling pad; and (2) although installing smcFanControl seems like a good choice, I dont think it gets at the heart of the issuei.e., the cause of the heating (it just speeds up the notebooks fan). It appears that CoolBook is the only undervolting program for Mac OS X, so I purchased it, expecting undervolting to be self-explanatory and easy to set up. I was, of course, wrong. Not being a computer expert, I searched for guides explaining how to undervolt, but most were too technical and jargon-riddled for my understanding. I continued to setup CoolBook anyway, and did the best I could, but am still not totally confident in my CoolBook configuration. So, Im going to explain step by step how I set up CoolBook on my Macbook Pro, and would like an expert to look over it and make sure I didnt screw up. Ive underlined sections that Im particularly curious/confused about. Note: I am well aware that CoolBook only partially supports Santa Rosa Macbooks (I had to look-up Santa Rosa). Im pretty sure my Macbook Pro is a Santa Rosa, as I only purchased it last May; this means it has a Penryn-based processor, right? Anyway, according to the CoolBook manual: The CPU of the "Santa Rosa" / LED MacBook Pro can be read and controlled using CoolBook, and the maximum power consumption may be reduced. There is however an issue, making this model consume more power running in idle battery mode with CoolBook activated. This does not really worry me, as I rarely leave my Macbook idle while running only on battery. Now, here are the steps I took: Download, purchase, and install CoolBook. Uncheck Throttling active. CoolBook active remains checked. Now, frequency-voltage pairings must be added to the Adapter. To do this, select each frequency in the frequency drop-down list one by one, in numerical order; for each frequency, also select a corresponding voltage in the voltage drop-down list. The goal is to select the lowest voltage possible for each frequency. Clicking Set will activate that frequency-voltage pairing, allowing the user to test whether or not the pairing is safe to use. This requires, however, some trial-and-error, because if the frequency-voltage pairing is unsafe, the computer will have an instant kernel panic, and shut down. (At this point, one would turn the notebook back on, reopen CoolBook, and select a higher voltage for the offending frequency.) To determine whether or not a particular pairing is safe, we use CPUTest (that is, if the computer hasnt already had an instant kernel panic). If the pairing passes CPUTest, click Add, and the pairing will appear in either the Adaptor list or the Battery list, depending on which is being altered. Next, click the Save button. Allow CoolBook to test the newly saved settings. Do this for each frequency in the drop-down list. (To reduce tediousness, I only ran CPUTest on the smaller frequencies and the larger frequencies. It became clear after a short while that all the lower frequencies would get the same voltage0.95 V, the lowest one.) Note: To be completely honest, I dont really understand how CPUTest works. All I know is its function for my current purpose: to test whether or not the active frequency-voltage pairing is safe. Here are the CPUTest options I set, some recommended by the CoolBook manual: Test type: CoolBook recommends selecting Huge, which I did for the smaller frequencies. For 2300 and 2400 MHz, I selected All, as it seemed like a more rigorous standard with which to test the frequency-voltage pairing. Repetitions: 1 (I can only guess that this option allows CPUTest to run the test multiple times.) Instances: I have no idea what this option does, but the CoolBook manual recommends selecting 2, which I did. Now, what exactly is B/2? The CoolBook manual reads: Check this box to use the frequencies with half bus speed. Santa Rosa only. When I check this item, the frequency drop-down list changes to include 600 MHz to 1200 MHz. As done with the earlier frequencies, I paired these with voltages, and added them to my Adapter list. After completing all the aforementioned steps, I ended up with the following list in my Adapter: 600 Mhz / 0.95 V 700 Mhz / 0.95 V 800 Mhz / 0.95 V 900 Mhz / 0.95 V 1000 Mhz / 0.95 V 1100 Mhz / 0.95 V 1200 MHz / 0.95 V 1400 MHz / 0.95 V 1600 MHz / 0.95 V 1700 MHz / 0.95 V 1800 MHz / 0.95 V 1900 MHz / 0.95 V 2000 MHz / 0.95 V 2100 MHz / 0.95 V 2200 MHz / 0.95 V 2300 MHz / 1 V 2400 MHz / 1 V Throttling level: Very High Temp limit: Off I repeated these steps for the Battery list (though it went much quicker), and the results came out exactly the same as in the Adapter list. Also, I dont know if this matters, but it made sense to me to unplug my notebook while configuring the frequency-voltage pairings in the Battery list. I figured that if Im testing the battery pairings, then the notebook should be running on battery. Was this necessary? Lastly, I turned on throttling by checking Throttling active. Other questions: Must I have a frequency-voltage pairing for each and every frequency? In some screenshots Ive seen, it looks like people have only a couple pairings. When setting the frequency-voltage pairings, should I be in Safe Mode? Does being in Safe Mode prevent instant kernel panics? In CoolBook Preferences, what exactly is the User/Password for? Is that only for notebooks that have multiple login accounts? Well, I hope that all made sense! Until I hear from an expert on this, Ive deactivated CoolBook to avoid any possible damage to my CPU. And, finally, here are my system specs, because I guess theyre important: Mac OS X 10.5.4 Processor Name: Intel Core 2 Duo Processor Speed: 2.4 GHz Number Of Processors: 1 Total Number Of Cores: 2 L2 Cache: 3 MB Memory: 2 GB Bus Speed: 800 MHz All help and information is greatly appreciated.