Passive radiators

[EMENCII]

Hi guys,

I was wondering how performs a passive radiator (no fans) respect if it has active fans on it... I don't expect exact results, but more or less?

Thanks,

EMENCII

[Archangel1994]

The cooling performance is massively decreased unless you got a big dual tower heatsink.

 

Passive cooling is not meant for powerful hardware but works pretty well on medium/low-end hardware

[JoaoPRSousa]

IMO, it's 30% more ineffective, but this is a shot in the dark.

[Zeke]

Are you talking about heatsink rads or watercooling ones?

[Kyuubixchidori]

entirely depends on the airflow of your case. i have a case fan almost directly behind my heatsink, so that could almost replace a cpu fan. but if you have no other fans nearby, itd be high temps. now watercooling rads, if you have enough surface area they dissipate heat fine. 

[AlwaysFSX]

You'd need a 9x120 rad to run passive at high temps.

[SMURG]

If you wanted to run a radiator passively, you'd want it to be a different shape. If you look at a radiator for heating a room, it isn't anything like a watercooling radiator despite the fact that they ultimately have the same function. The reason for the difference is that watercooling radiators are designed to have air moving over them, whereas heating radiators are intended to radiate the heat into a room on their own.

If you think about the fins on a watercooling radiator, if there is no air movement then there is actually very little air in contact with the fins, since it's the same air pretty much all the time. Stick fans on it though and the volume of air exposed to the fins increases by several orders of magnitude since the air between the fins is being replaced all the time. By contrast, a heating radiator relies on convection of air in the room to generate movement over a far smaller number of much larger fins.

If you run a watercooling radiator passively all you've done is to effectively create a reservoir which does a slightly better job of losing heat than a normal one - and the higher the fin density the worse the performance will actually be since air will simply become trapped in the smaller spaces more easily and fail to remove any heat at all.

[EMENCII]

The cooling performance is massively decreased unless you got a big dual tower heatsink.

 

Passive cooling is not meant for powerful hardware but works pretty well on medium/low-end hardware

Watercooling radiators, not air coolers ^^'

 

Are you talking about heatsink rads or watercooling ones?

Watercooling...

 

entirely depends on the airflow of your case. i have a case fan almost directly behind my heatsink, so that could almost replace a cpu fan. but if you have no other fans nearby, itd be high temps. now watercooling rads, if you have enough surface area they dissipate heat fine. 

There's none, because the rad would be outside...

 

You'd need a 9x120 rad to run passive at high temps.

What about Jayztwocents' Skunkworks? He said 10°C and it has 4*120mm and 4*140...

[AlwaysFSX]

What about Jayztwocents' Skunkworks? He said 10°C and it has 4*120mm and 4*140...

His aren't passive.

[EMENCII]

His aren't passive.

He, one time, said that the delta T passive/active was 10°C, both the GPUs and the CPU... So i was asking for that... A percentage