How often do you guys air dust your PC? A little amount of dust on the heatsink can easily raise temp around 10c.
Also, it's very important to take cooling into account, many things including computer case, fan position, etc. may affect your CPU/GPU heat dissipation.
Take the most demanding game you play and note the average CPU/GPU temps, after 10 minutes, then remove your case cover and do the same. If temp raises more than 5c your PC has poor cooling performance. Depending on how close the closed case temps are to the maximum recommended for your CPU/GPU you can ignore it or fix it by air dusting (vacuum it at the same time, otherwise the dust will be back inside in a couple of days), changing to a better case, most gaming oriented cases from decent brands do a good job, switching to more efficient aftermarket heatsink/fan, run with your case open (more dust, risky), or, run your games on lower settings.
____________________________See your face upon the clear water. How dirty! Come! Wash your face!