Darkbreeze :
epson :
i think the correct answer is no, it isn't. But highly highly recommended. Put it on and then check your temps, they will be alot higher, but i would guess still well within safe temps. Metal to metal transfers heat just fine, but there are tiny bumps on the surface, the paste fills these in. However if u do what i said, its at your own risk. That being said, most if not all modern equipment has temp sensors that will shut themselves down when they get to hot, so in my opinion, not much risk.
And you're a fool if you think thermal paste, even if it's just mayonnaise, isn't necessary. And not that anybody is going to listen to that nonsense anyhow, but it's pretty irresponsible to try to pass the idea that it IS ok, on to somebody who might actually take you seriously. If you actually believe that nonsense, you need to start over from scratch and do your research. If it WASN'T necessary, we wouldn't even be having this conversation. I guess in a sense you're right, but by that way of thinking, it isn't really necessary to put oil in your car either. Oh, it will run without it, for a while. And it will shut down when it gets too hot too. Unfortunately, it tends to cause irreparable damage, just like repeatedly overheating a cpu to the point of thermal shut down does. You should be more cautious with your advice, lest you cause some inexperienced novice who isn't going to pay any attention to their thermal readings on any regular basis, to take you serious.
i was very cautious with my advice, i gave plenty of warnings. But you also have obviously never put a heatsink on without thermal paste before and monitored what happened. In my first hand experience, nothing bad happened, ever. maybe i was lucky, or maybe your just passing on advertizement that thermal paste companys have shoved down our throats for years. Paste is designed to HELP transfer heat, and btw there are alot of cases where thermal paste HARMS the transfer of heat, aka badly applied, old, generic brand that insulates instead of transfering heat, ect ect. Until u, yourself, actually does it, u shouldn't comment. Its smart to use thermal paste sure, it will lower your heat sure, but u do realize what modern cpu's and gpu's are rated to withstand heat wise right? my "guess" is the only way u would maybe reach those temps without thermal paste is if you're using the stock coolers.
Lastly, don't call people fools. This is a debate, no need for personal attacks, sometimes being wrong or misinformed is hard to deal with but try to take it as a learning experience.