Fan pulling through resistance make unavodable bad noise?

[baii]

I recently tried to add a pull fan(ty147a) to my macho hr 02 and the pull fan make significant worst sound in quality and quantity compare to the push fan.
at low rpm (below 500) it is rather indistinguishable , but once rpm go higher, it easily surpassed the other fan.

Also, pulling through grill/mesh with most fan seem to sound worse than pushing.
Is this a problem specify with my heatsink, or something universal? Or it is the distance that matter? As push tend to be further away from the object for a little bit.

[quest_for_silence]

Part of your problem is that the pull fan may actually spin faster (slightly) than the push one (it is "accelerated" by the flow coming from the push fan itself).

[xan_user]

I recently tried to add a pull fan(ty147a) to my macho hr 02...

can i ask what the high temps and highest rps were? i.e what made you want a second fan?

[baii]

For the sake of tinkering.

Turn out it is just that way when a fan pull from the heatsink, no matter front or back.
It is back to one fan now.

[doyll]

One of us must be the bad penny. We keep running into each other

I had a play with my Macho and below 850rpm I can run 2x fans in push / pull. Got called back back by SWMBO before could do more. Will try to remember and check it out more when I get time.