SPCR

OK, I'm thinking like this: The more area across which you're pushing air, the quieter it is. (For example, 4 fans at 5v is a lot quieter than 1 fan at 12v for the same CFM.)

So you'd like to put a 160mm or a 240mm fan on your CPU HS if possible.

Well, that may not be practical.

So then you should use positive or negative *case pressure* to push/pull air through your HS. You can produce whatever level of airflow desired if you have enough case fans, the case is sealed, and the only exit from the case is through the CPU heatsink duct.

The nice thing about doing this is that your case is physically big, and has room to mount a great number/size of low-speed fans, possibly.

The only objection I see is that fans (particularly propellor type fans) will lose a lot of airflow if fighting pressure. Hence, you'd need a wide duct with low impedance as your HS/case exit duct. This implies you're using a big heatsink, like a Zalman 7000.

Or use blowers. Lots of quiet low-speed blowers.

thoughts anyone? Has this been thoroughly thrashed out elsewhere?

the wesson

TheWesson wrote:the case is sealed, and the only exit from the case is through the CPU heatsink duct.

Maybe I'm not following you but isn't this like pre-heating the air used to cool the cpu?

TheWesson wrote:OK, I'm thinking like this: The more area across which you're pushing air, the quieter it is. (For example, 4 fans at 5v is a lot quieter than 1 fan at 12v for the same CFM.)

So you'd like to put a 160mm or a 240mm fan on your CPU HS if possible.

Perhaps you would like to mount a 240mm fan on your heatsink, but it's useless. It would need to have some 800 RPM to devellop enough pressure to push enough air through the heatsink.

TheWesson wrote:So then you should use positive or negative *case pressure* to push/pull air through your HS. You can produce whatever level of airflow desired if you have enough case fans, the case is sealed, and the only exit from the case is through the CPU heatsink duct.

The nice thing about doing this is that your case is physically big, and has room to mount a great number/size of low-speed fans, possibly.

When you use suction the fans probably end up further away from you, and the case doesn't need to be airtight.

TheWesson wrote: The only objection I see is that fans (particularly propellor type fans) will lose a lot of airflow if fighting pressure. Hence, you'd need a wide duct with low impedance as your HS/case exit duct. This implies you're using a big heatsink, like a Zalman 7000.

Or use blowers. Lots of quiet low-speed blowers.

Nope, not that I'm aware of. There are no quiet blowers.
Wouldn't you think we would have used them if they were quiet.

Alas, I've failed completely to convey my vision ... !

What I mean is: Use case fans to move air through the heatsink. They can be many and/or large (hence quiet for the CFM they move.)

In other words: A sealed case with a ducted Zalman 7000 heatsink, perhaps with no fans or a minimal fan on the HS itself. Mount 4x Panaflo@5v moving case air in or out (you can bury them into the case with a duct.) Nearly all the air going through the case has to go through the Z7000.

that's the idea.

the wesson

PS with positive case pressure, you could remove your PS fan I would think.

Ok, I think I'm gettin a visualization. A twist on cpu heatsink ducting? or maybe I'm not gettin' it.

Yeah! Yeah! A twist on CPU heatsink ducting! With minimal fannage on the HS!

the wesson