I was looking for the answer to my problem and googled it not finding many common answers, so I'm posting this just incase anyone wants to do the same
So here was the situation. I owned a Latitude D620 from Dell. However, it's heat was INSANE. I had a laptop cooler running with it, and fans on high and all times, and even undervolted it, yet it was still approaching huge temperatures. It wasn't uncommon to see 100 degrees celsius as it's peak temperature. I might even idle around 60 degrees just web browsing! Many of my games started to encounter extreme lag from the heat.
So, I finally decided to take apart my laptop. Not a happy decision as I find taking apart laptops more annoying and complicated compared to desktops after having disassembled my Inspiron 1520 awhile ago.
Anyways, next to the fan, i literally find a wall of dust, blocking the entire exhaust of the fan. It's practically like it was useless! Then, I lift up the heatsink and find the thermal paste just a huge glob.It spilled all over the CPU (no integrated heatsinks being a mobile Core 2 Duo) and was very thick. So I dusted the fans, removed the Great Wall of Dust, removed the generic thermal paste, and applied my Arctic Cooling MX-2 (Which I love so much!)
Now temperatures are more like:
I had the same problem. Decided to take my dell apart and also found the great wall of dust there. And the thermal paste was all over my CPU the same way. So I decided to replace it with arctic cooling MX-4.
But as I removed the heatsink it tore apart the thermal pad on some other unit(probably GPU) which was also connected to the heatsink. Did you replace your pad also? Or did you just left it there? I have searched the google and found out that most people find the thermal pads a cheap option and recommend replacing them with paste. On the other hand I see that applying a thin layer of paste there might leave a gap.
I really need some good advice here..