120mm Fan on P3125?

Well... i'm getting tired of the two delta 38's on my old P3125S heatsink and i was thinking what my options were to find a way to quite down my pc. I've came up with the idea to build a 60mm to 120mm adapter so i could fit a Panaflo 120mm ~85CFM fan.
The 60-120 adapter will probably be made out of the glossy side of poster board. I'm wondering if anyone has tried anything similar, and if i would be increasing or decreasing performance.

well the problem you will have is static pressure. box type fans dont have a lot. when you take a fan that puts out 85cfm with no ristriction and give it half (ok a little more than half with the hub) the space to push that through you build back pressure. this is ok if you can match the back pressure to force the air through at a higher volicity (venturi effect) but the fans we use do not put out enough pressure. i have tried to do this and did not get near the air flow of my regular fan. your best bet would be to get a little noisier (but quieter than your screamers) 120mm that puts ou tmor air or to try a 80 or 92 mm fan. if i am wrong in any of this please correct me but i beleive it to be te case through my studies

edit: oh and this should be in cooling for future reference

Okay, now you gone and confused me... Is what it sounds like your saying is the that air in thats in the funnel like 60-120mm adapter will want to push the oppisite way back through the fan.
Is that whats going on? If I got it right, then it sounds more like a problem with the speed at which the fan spins, not the size... You said a faster 120, which will just spin the blades of a similar design faster which will create greater pressure...

If I were to go with a different fan size, like a 80mm or 92mm, I would be using two to compesate for the current two fans on the heatsink, and would that create a simmilar problem that you were stating in the first situation?

I miss my Alpha 3125, I gave it away to the person that bought my PIII

Anyway have you just considered using a Rheostat? Thats what I did, adding dual fan adapters will not be easy, actually I dont think its ever been done for a reason.....reason being its a difficult task....correct me if Im wrong on that.


Hoot sells some of the highest quality Rheostats you can buy.....Shoot him a PM and ask him to sell you one.

Don't tell him I sent you or he will charge you more

Save yourself some time and try using the 7v trick first. I also have two Deltas and they're substantially quiter. If it's still too loud, then consider making your adapter. My only suggestion is that you mae the adapter's size to be 120mm x 120mm -> 60mm x 120mm. That way, the entire heatsink will still have air going through it.

i think i have a better picture not what you need to do is make, as cow said, a 120x60 adapter and that will work better than a 120-60 square adapter. it will still have a little pressure but the extra space will allow more airflow. try to make the mounting points take up as little space as possible. this setup should work better than two deltas. assumeing you use about a 90cfm fan. is this for a slot porcessor? if so you will need to make it gow up away from the mobo. if you would like i can draw a quick sketch in paint, just PM me with details about your requierments.

okay, i apologize about the lack of information and the delay in response...

i have a slot 1 P3 700 @ 936mhz. I'm using the Alpha P3125 fan/heatsink. It's a fairly large heatsink with two 60mm Delta fans on it. I want to put ONE 120mm fan on the heatsink and replace both Deltas.

Now the adapter opening will be 120mm x 120mm to accomidate the larger fan. The adapter's exit will be 60mm wide, but 120mm long (two 60mm fans side by side).

I'm including pictures of the drawings of the adapter. I didn't make any dimensions for the height cos i haven't made any measurements in the case.