How do you attach a fan to a radiator?

[Jon Joel]

So bear with my crappy type drawings. I is the inside of the case, o is the outside of the case, R is the radiator, f is the fan and > and < are the direction that the fan is vlowing directly . I know 2 of these are right and 2 are wrong so please tell me which.

O F>R I
O RF> I
O <FR I
O R<F I

Does this make sense? I'll try and think of a better way to explain if I need to.

 

[ThatVietGuy]

The usual setup should have air flow from inside to outside - so that eliminates the first two.

The best setup is the fourth one since you usually get better cooling by blowing over the radiator, rather than pulling air through it.

In the end, there's no right or wrong way, really, just what suits your system best.

 

[Jon Joel]

Why inside to outside? if it's the fourth configuration isn't it just blowing hot air though the radiator from the inside of the case to be cooled then go outside the case? I don't understand how that's good do you mind explaining that to me?

 

[ThatVietGuy]

Taking air from the outside to inside would be best for the CPU, but it would affect the rest of the computer (e.g. GPU) since you're blowing hot air into the case. This is why most people opt to take air from inside the case (obviously a little warmer than the ambient air) and exhaust it through the radiator out the case.

Like I said, this is just the common practice. You can try whatever combination you want and figure out the setup that's the best for you and your setup.