Newer, more powerful and power hungry computers generally bring along with them a rather irritating problem - Heat.
If not dealt with properly, it can cause a few issues like constant restarting of the computer, shortening of system life or in worst cases, the system to go Kaput ! (die).
The CPU and Graphics card are generally the major causes for the heat generated, there are many ways to get rid of it, some are hard and expensive, and some are really simple and effective.Cooling solutions for the CPU (processor) :
Let us assume you have not overclocked your processor and you are using the stock CPU heat sink that came with your processor. If your processor temperatures are in the mid 40s or below, there is not to worry and your CPU is cool enough. If the temperatures are in the 60s or more, then you have an issue.
If you have some money to play with, you can get a cheap aftermarket CPU heat sink fan to replace the stock fan, a few good options are the Cooler Master Hyper TX3, cooler master Hyper 212 plus (you need to take care about the size) and the ARCTIC COOLING Freezer pro (select according to socket). These can set you back about Rs1600 ($40) but are almost sure to bring those temperatures back under control.
If you already have an aftermarket heatsink fan or you don't have the money for one, you can apply some good quality thermal paste. Remove your existing HSF and remove the older thermal paste from the processor and the base of the HSF using some isopropyl alcohol or you can even try brake cleaning solution (for cars). Re apply paste and re attach the HSF. Make sure its properly seated. If you want to know how to properly apply thermal paste, have a look at this video:Cooling solutions for Graphics cards :
The newer graphics cards are becoming more powerful and are getting hot too. They can reach temperatures around 90C and at times even 100C at load, these temperatures are far higher than ideal (which is 70C).
With such high temperatures, you are left with a few options. One is buying an aftermarket cooler for the graphics card. These are not very easily available in india, but if you are from the US, you can easy shop them off newegg or amazon. Choose them according to their compatibility, all heatsinks don't fit all cards.
If you don't have that option, what you can do is reapply the thermal paste on the GPU and memory chips on the graphics card. You may require thermal tape for the memory. Clean the stock heatsink of the graphics card cooler. It is the easiest way to drop the temperatures, dust can clog the heatsink making it practically useless. This trick worked for me, the temperatures of my 4850 reduced from 100C to some 66-70C by just cleaning the heatsink.
Well, all this is only useful when you have a well ventilated system. If your system is not well ventilated, the hot air will remain inside your PC and slowly cook you PC. Hence, its always better to plan it properly.
I feel every PC should have at least 1 intake fan and 1 exhaust fan. Their placement can be varied according to needs. If you want to cool your graphics card particularly, its a good idea having a side fan blowing air into the card. The bigger the fans the better as they push more air at lower speeds (hence less noise).
1 Fan in front (intake) , 1 in the rear (exhaust) is enough for more mid range PCs, for high end ones, its best to have a side fan (Intake/exhaust according to needs) and 1 top exhaust fan. Good chassis come with plenty of options for fan placement, one of the best chassis in terms of airflow are the HAF 932/922. They are pretty good in terms of value for money and have one of the best airflow. Its always good to invest in a good chassis as it can help in dropping the full system temperatures.
I hope i must have cleared some doubts about system cooling, if you still have any doubts/suggestions, feel free to post them here.