My MacBook has been running hot recently, idle temps in the 140-150F range, watching vids on YouTube or other streaming sites pushed it almost to the point of overheating (190-200F, fan running at max speed, video starts stuttering, occasional browser crashes)
I pulled the top case, removed the main cooling fan and heat sink, removed some dust bunnies, reapplied the stock Apple thermal goop, and tested it
idle temps remained around 140ish, streaming video brought the processor to around 170ish, the fan still ran mostly in high-speed mode, better, but not acceptable
So, a couple days ago, I pulled the top case again, removed the fan and heat sink, cleaned off the Apple thermal goop, and replaced it with a layer of Arctic Silver thermal transfer compound (I think it’s AS-5)
the difference has been dramatic, according to the manufacturer’s website, it takes a few thermal cycles for the product to reach maximum effectiveness, and that’s been the case here
Day 1; idle temps 140ish, 175ish under load, fan still running fast (6,000 RPM)
Day 2; idle temps 135-140ish, 160 under load, fan running slower, only fast under load (5,000 RPM)
Day 3 (today); idle temps 130-135, 145-155 under load, occasional spikes to 160, fan all but silent except when under load, and even then, fan speed is half or so of what it has been (3,500 to 4,000 RPM)
I am quite pleased with the AS thermal compound so far, it has made a dramatic improvement in the heat management system of my MacBook, I may just break down my Mirror Door G4 tower, and iMac G4 17" and replace the Apple thermal goop on them with AS as well, this stuff is worth it, excellent performance, highly reccomended