Fixed Macbook Air From Skipping When Playing Flash Video (Hulu, Youtube)

The Problem: Video sites like Hulu and and Youtube play video through Adobe Flash. If you look at the cpu usage for playing these videos, it’s much higher in OSX or linux than when playing flash movies in Windows. Why is this? Clearly Adobe has optimized flash to run fast on windows and has not bothered to optimize it in OSX or Linux.

Let me be clear here. Flash is really dog slow in OSX, and it’s not Apple’s fault, or anyone’s fault except Adobe.

That said, now we come to my macbook air Rev A, boasting a 1.6Ghz Core 2 Duo processor. Hey, that’s a pretty fast processor. Steve Jobs said so. So then, why can’t I watch a movie on my computer. I mean, ok, flash sucks, but does it really suck so bad?

Well, it turns out that my core 2 Duo 1.6Ghz is actually running at 800Mhz most of the time. Why is that? It runs cooler at 800Mhz, and apple designed it that way to run cool.

If a core 2 duo processor exceeds around 105 degrees centigrade, it burns up. If 1% of macbook airs burned up, Apple would be drowned in repairs and returns.

So, what happens when I watch a movie on hulu, is, my cool processor initially is running around 800Mhz, I start the movie, and my cpu goes to 40% load, and OSX cranks it up to 1.6Ghz. After about a minute, the cpu gets to around 65 degrees, and OSX decides that’s too hot, and cranks it back down to 1200Mhz or even 800Mhz.

The movie actually runs ok around 1.6Ghz, so the goal here is, how do we keep our computer there most of the time? Well, the short answer is that we tell it to with Coolbook . By setting a Temp limit of 85 degrees, we say that the computer can run as fast as 1.6Ghz until the computer gets that hot, which is pretty hot, but it still shouldn’t damage your CPU. I’m willing to take that risk, even if Apple isn’t willing to for me.

Next on the agenda is how can we keep the computer cooler, so we don’t actually get to this 85 degrees hopefully. Good ventilation is a great strategy (putting the laptop on a hard table instead of your lap). Another weapon is “undervolting”.

The idea with undervolting is this. Intel makes a bajillion processors. Maybe 99% of them can run at 0.9 Volts, but 1% need at least 1.2 volts to run properly. Apple doesn’t have time to test each CPU individually, so it just sets them all to run at 1.2 Volts. Power consumption I believe is a function of Voltage Squared. So, if you scale down from 1.2 to 0.9, I think you should expect cpu power to decrease to 0.9^2 / 1.22^2 of full power, or around 56% of full power. This means that you should notice some battery lifetime improvements as well, but LCD probably is what uses most of the battery anyway. Coolbook also lets you do undervolting. I’ve posted my settings below. Basically, I’m lucky enough that everything seems to fun fine for me at 0.9v on my cpu.

Coolbook costs $10 to use. This may seem like a steep price to you linux users who are used to changing cpu clock speed by just changing a number in some file in /proc . However, it really finally makes my air much more usable. And I’d recommend this option to all air users before giving up on the air and buying a new mac.

my coolbook settings