Do both parts of this kind of CPU need thermal paste?

Hi

I would apply to both personally, BUT surely it would be obvious if the smaller area had been pasted before by touching it?

The paste should be spread thin like old fashioned Margarine, not thickly like Butter.

Hi

Magic.

The paste is to fill the tiny tiny cavities on the surface of the 'CPU' leaving an even 100% contact area.

https://community.amd.com/t5/processors/change-of-thermal-paste-and-thermal-pad/td-p/358148

Hi. I just applied it. And when I checked the heatsink, there were 2 kinds of material. One was copper/orange colored. The other one was normal grey color. 

The copper color was for small IC. The small IC of CPU itself was shiny and clean. The bigger IC was messy with grey paste. 

So I just cleaned the grey paste from heatsink and bigger IC and didn't touch touch that copper colored material on heatsink.

Here is a photo you may want to see: Imgur: The magic of the Internet

Did I do the right thing?

download hardwareinfo and check your thermals. If anything is near 90-100C, you gotta put thermal paste on both.

It's just thermal paste - it can't really hurt anything. If the heatsink comes in contact with both of them, chances are you need thermal paste on both of them. The CPU die is the bigger one and the iGPU is probably the smaller one, and that needs cooling too. You'll notice those temps spike any time you play video or play games.

Ah I didn't knew the smaller thing could be the iGPU.

BTW I play games with NVIDIA gpu only. iGPU works mainly for maybe display only or very light apps.

So technically iGPU shouldnt heat during gaming right?

Unless you are using a device with a MUX switch (expensive gaming laptops), the NVIDIA works along with the iGPU. It's called NVIDIA Optimus. So while the NVIDIA is doing all the work, it's still outputting into the iGPU and then to the display. so the Intel is always working all the time.  I can't say how hard iGPU works during gaming, though, probably only when you hop into the desktop. If you have a monitor directly attached to the HDMI, you can cut out the iGPU, that's the exception. Playing video will get your iGPU to work hard - I'd play a 1080p or 4K video and then look at your temps.

Okay.  I just installed the software you mentioned hardwareinfo and I noticed when no games or videos running, CPU temperature were around 50 C.

When gaming CPU reaches 80 C. GPU doesn't go up from 72 C. (Earlier CPU would reach 90+ C and GPU would reach 78 C).

However, before changing thermal paste, my GPU core clock won't go above 405 MHz at all on heavy games like GTA V. Now it sometimes reaches 950+ MHz and game become much better and smooth.

But it keeps fluctuating. 2 minutes 950+ MHz (GPU Temp = 66 C), next minute 405 MHz (GPU Temp = 70 C). And game becomes slow like before replacing paste.

Is this normal on this kind of GPUs?