I wanted to ask if there is only one kind of thermal paste,or are they specific like "cpu paste" "gpu paste".
Also,when replacing a cpu/mobo how can you clean the old paste and how much do you need to put again?
For those that don't know, TIM = Thermal Interface Material.
There are different kinds of TIM, but not like your thinking. The original performance TIMs contained silver. Silver has excellent heat transferring abilities and works well as a TIM. Newer ones are taking advantage of carbon by adding crushed diamonds or carbon to their TIMs. They don't have a dedicated usage per se, but if you aren't dealing with a lot of heat there is little point in buying the best of the best.
You clean the old stuff off by using rubbing alcohol. Use a Q-Tip for any hard to reach places. You actually need very little when you put more on. How much and how to apply depends on the type of heatsink, who made the TIM, and who you ask. I'd follow the directions on the sink/TIM.
Paste not Specific, this paste same using for all purpose GPU & CPU conducting with Heatsink.
Clean with alcohol isopropyl / more hard use M3 (oil for Printing), all clear
replace New Thermal Paste your CPU & GPU cold.. cold ..cold
The youtube video is interesting, but only for "normal" HSF. With direct contact heatpipe coolers like the Hyper 212+ you should work the TIM into the groves that naturally occur with that type of cooler. If you don't, there will be a large pocket of air next to each heatpipe. Those methods work with completely flat coolers, but as I said it will depend on the cooler you use.