Cooling my mbp, undervolting it… need advice.

Hey guys,

Anybody here who owns a macbook pro will know that the thing gets DAMN HOT . Right now it’s idling at about 55-56 C. Apparently they get up to 100+ when running full force. I did some research and found that coolpads don’t work really well for mbp’s because mbp’s don’t have vents at the bottom. I found out there are fan control progs that allow me to raise my fans to a max of 6000 rpm (apple has them limited at 2000 rpm) but I found out that the most effective way to cool a mac and make it more efficient is by undervolting it.

Has anyone here ever undervolted a macbook pro or any laptop in general? What should I look out for other than kernel panic screens?

Help?

For anyone who has no idea what I mean, here’s a guide.

I’ve never heard of undervolting before, and have used a few mbp, all of them overheat. what I usually do is place it on two stacks of books, so it cools and that works a bit, and otherwise I just put it on the table, if you have a cat that’s nice for the cat, because he/she will then like to lie on the warm spot after you removed the computer

I bought this:

http://www.coolbook.se

I found my mhz/voltage pairs and now I am running stress tests on the machine. It appears to have been cooled down, mostly when I start to stress it. It doesn’t go beyond 72/76 C atm.

Btw this could also be done (and is recommended apparently) for windows laptops.

And Pandebus, how does placing it ok stacks of books help? MBP ’s do not have vents at the bottom, they have a vent outlet near the hinge and at the speaker holes.

but that way the air still reaches it, same principle as putting a pot of boiling water next to the stove, you don’t need vents for that personally I somehow find that using my MBP is most comfortable in the winter…. I wonder why

but that way the air still reaches it, same principle as putting a pot of boiling water next to the stove, you don’t need vents for that personally I somehow find that using my MBP is most comfortable in the winter…. I wonder why

Yeah but a pot of boiling water has a stark contrast temperature between the pot and the environment as well as a body of water inside and a more conductive material in between. A case is less conductive and contains a lot of air (one of the best isolating materials). I am unsure as to how much this actually saves you.

Besides that, the pot of water does not have a heat source powering it, if your mbp is on, it has a heat source. So unless you are turning it off while putting books under it, I really don’t see the use of this technique.

very interesting topic Arik…reading the guide…

Actually, elevating the MacBook Pro up off of a table top or similar surface would help cool it. That wouldn’t be the case with a laptop with a plastic casing, but since the MacBook Pro is aluminum the entire case essentially acts as one large heatsink (which is also part of the reason why it seems to run hotter than most non-metal laptops: the heat is radiating out through the case, instead of being insulated inside of it- that, and Apple purposely keeps the fan RPMs low to reduce noise).

I personally use the app you mentioned, smcFanControl, and it works wonders for keeping my machine cool.

The problem is that heat kills parts and especially MBP ’s tend to fry. Buying a cooling pad won’t work because MBP ’s have no vents at the bottom.

Stress test normal conditions: 82-92 C. (10 min test). Stress test undervolted: 70-72 C.

I’ll do more testing in the coming days.

The guide I posted is for Windows!!!! When you buy Coolbook (see second link) you get a guide with it for Mac, much easier through that prog btw.

Here’s the principle:

The more volts your chip pumps out, the more heat it creates. A minimum stable voltage is different for each individual chip (NOT each model, each chip!) and that’s why companies can’t be bothered finding that voltage for EACH system so they just set a safe high voltage.

What I just learned is how to find two cycles/voltage pairs. First I set it to the lowest voltage: 0.9375V and starting ramping up the cycles until my mbp crashed. I got to 2527 MHz (at 2660 MHz it crashed). Then I put the cycles at max and started dropping the voltage. I got 0.9875V for max cycles (2793 MHz, I have a 2.8ghz mac, it’s that easy). This is two “notches” above the voltage at which the system crashes.

OK, So now I have two datapoints.

0.9375V @ 2527 MHz
0.9875V @ 2793 MHz.

I now know that my chip will run a MAX of 2527 MHz at the lowest voltage to achieve top performance and it needs AT LEAST 0 .9875V to run at MAX .

Now I setup the program in a way that it throttles (aka switches) between these values and a few values in between depending on how much my mbp needs.

I added smc fan control and dropped my idling temp to 42 C, without anything I was idling at around 55 C.