I, too, doubt the effectiveness of the internal air flow --- either due to the dust or to the inappropriate internal aif flow design.
Have you already measured the temperature of the CPU and rpm of the fan? Both for normal time and at the time of the overheat.
1) If you need a free software for it, this is one of them. (For measuring temperatures of CPU, PSU and HDD as well as for CPU fan speed)
2) HDD's also overheat and for more detailed diagnosis of them (both internal and external), also a free software is available.
(this gives you not only temperatures of HDD's but also health status judgement, power on hours, how many time you powered on/off HDD'S, etc. - lots of tecchy information which I donot understand.)
This is a Japanese site but simply change the language to English after installation.
3) this is NOT related to this issue but one more free software that gives you lots of info about CPU...
Choose appropriate version depending on which Windows version you use, 64-bit or 32-bit.
I personally use all of them for years and they have not created any problems while using my PCs.
External note pc fans. Much cheeper solutions. Samples are shown here; This is Japanese Amazon site - I have difficulty in finding a similar one in US Amazon site.
You can use this even for your new notebook. It worked for my old notebook before. When your notebook does not have fatal defects, which I think is less likely as two years of usage is just very short, imo, then this simple equipment probably helps.