Top case rad question

OK, so i'm over in another forum and a guy asks if he mounts a 120.2 rad at the top of the case what direction does the fan need to blow.. into or out of the case...

so i'm currently in this discussion because someone says blow out of the case...

what gives the best temps.. using ambient air to blow into the case over the rad or use case air to blow out over the rad?

i would make is blow in. Usually when they say for a rad, you want cool air to blow inward.

but then that's forcing cold air into where the hot air's trying to get out

I have mine blowing out. It works quite well, as the system temp is only about 4ºC over ambient.

I personaly do not have a rad in the top of my case, this is just my logic on it. If you make it blow out of the case your getting all the hot air produced by your mobo, vid card and some from the hardrives. If you have it blowing in you get cold air but then the hotair would only be able to get out of the back of your case. You would have to pick the lesser of two evils. I would think that it would vary from system to system and depend on how the rest of the cases airflow is(for example if they had weak/no rear exhaust the rad would get alot more hotair than if the case had good rear fans). If there is good airflow out of the rear of the case i think that it would benifit eather way.

edit: pretty much the same as the post above

if you have the fans blowing out of the case, you are taking the HOT air from your case, and putting it through your radiator. this will yeild better case temps, but worse cpu temps

if you have the fans sucking air into the case, you are taking COLD outside air, putting it through the rad (which cools the rad, but heats the air), then putting it into your case. this will yeild lower cpu temps, and higher case temps.

i would say try it both ways and see which gives better results. i would think you would want lower cpu temps.

ok so this guys logic was if you cool the cpu and gpu then there is minimal heat in the case. i countered with not all of the cpu/gpu heat is 100% efficient in heat transfer so you lose heat to inside the case.. also the psu will dump heat into your case even though it vents to the rear. his argument was that HDD/CDrom/NB heat is so minimal that it's better to dump the air that is heated by passing through the rad into the ambient.

so hes saying that the case air isnt too warm, so its ok to put it out through the rad?
i dont know why you would want to do that. if you are trying to cool your cpu and gpu as best you can, then putting the coldest air through the rad is best. the case temps will be higher, but the components that need cooling are for the most part taken care of, and if you have exhaust fans (i would make the front and rear both exhaust), then you should be able to take care of case temps.

Theres still heat comeing off the ram, mosfets, northbridge(maby watercooled), southbridge, ect. I would think that both ways would have to be tried as there is alot of factors.

devilscow22 said:

Theres still heat comeing off the ram, mosfets, northbridge(maby watercooled), southbridge, ect. I would think that both ways would have to be tried as there is alot of factors.

Click to expand...

No. The mosfets and the southbridge are hot, but they do not transfer this heat to the air very well. This is why they ARE hot. There is relatively little wattage going through them. The northbridge I can understand, but when you remove the GPU and CPU heat from the case you are left with low case temps anyways. Do you think a hard drive will heat up your case like a CPU and GPU will?

Logically, this makes more sense than blowing in because you can take advantage of conection currents as well.

I've 2*120 fan heatercore at the top the dragon fulltower case. I tried both (in and out) and didn't notice any difference in the tepreture of the main componenets. There was a difference when other fans was added/removed.
so the general answer is - it depends. depends on the air circulation in the case.
i've chose blow out configuraion, so less dust will be trapped in the heatercore.