I take it that you are either having problems with thermal throttling or are overclocking.
[Warning: Overclocking can damage your components]
Make sure that if you are overclocking that you go up in increments on the clock speed and Voltage. Test run it at each new speed to see if stable. Overclocking generates extra heat and suitable precautions ought to be taken before embarking [go to 5].
Improve your airflow by tidying your cables. Proper cable management will improve the passage of air through your case.
Use decent thermal paste as the stuff that is on stock fans is okay but you can get better performance with the aftermarket stuff.
Crank up the fans; if they are running very slow the air will not be displaced quick enough to cool the ambient case temperature [Warning this can get very noisy and is not recommended for HTPC setups go to 5].
Clean your case. A build-up of dust within your case will cause your components to overheat. If your case does not have filters then a good clean will help. Most people tend to keep their PCs on the floor under their desk where airflow is not optimum.
To achieve a better result, change your current Air Cooled CPU Cooler. There are a number of sealed liquid cooled CPU Coolers on the market at very reasonable prices which would reduce the heat from your processor. If you can afford it go for a fully blown liquid cooled system which could also cool your GPU or refrigerated PC case, both of which are expensive.
Article on CPU Coolers:
Not sure if anyone is still making them but here is an example of the refrigerated PC case:
If you want to get extreme: