Build the best CPU exhaust duct.

[Bluefront]

You can argue about this claim, but until I see something that works better, is easier to make, and is cheaper......I stand by my claim. For this project you need two things: an Alpha 8942, or an 8952. The photos show an 8952....about $30 at Newegg w/o fan. You also need the duct, a Smart Choice Dryer 90 degree Close Elbow. I got mine at Best Buy for $8.

The pictures show the technique. You need to slightly bend in the corners of the fins on the Alpha....that's it. The upper right corner of picture 3 shows the angle.

The duct itself can be bent easily by hand. You work at it till the duct just slips over the Alpha.....it's snug but movable once installed. The stock shroud of the Alpha leaves 1" of fins showing at the base. This is what you want when the whole thing is installed. If necessary you can trim the aluminum to get to this spec.

On the other end you'll have a 92mm fan of your choice....The Aluminum Evercools probably couldn't be attached like this. You cut off the flanges on one side of the fan frame. Which side you cut depends if you want the fan to blow or suck. Sucking works better with this Alpha.....but the photos show a fan cut to blow.

The fan can be attached to the duct simply with duct tape....or more elaborately with a rubber gasket. The fan is then attached to your case any way you please (I used cable ties).

You will probably have to re-cut the rear case hole to match the fan. Not hard to do.....you can fill in any openings with a plate cut out of a piece of sheet aluminum. Like if you already had a 120mm hole in the case, a sheet of aluminum with a 92mm hole would work.

A 92mm fan is plenty to cool off a Prescott.....already tried it.

I have tried this setup on three different case/MB combos. There is enough adjustment possible to get it to fit many different setups. If you attach the fan to the case properly, you do not have to attach the duct to the alpha. It's a snug fit....won't move.

Also you can open up the bottom flange of the duct to draw in more air over the Northbridge heatsink.

That photo at the top of this post shows this setup installed in a dbox case, with a P4 2.4. It idles at 33C with a max temp of 42C with the fan at 1500rpm....blowing out. The rest of the case stays very cool with this duct blowing out.

IMHO.....this is the best air-cooled setup you can build, all factors taken into account.

Ten photos

[Bill Dunsmore]

I have an Alpha PAL8045 with a Papst 1500 rpm fan blowing up. I cut a blowhole in the side of the case directly beside the HSF/fan. The power supply is a modded Zalman with an air duct to the front of the case and a Panaflo running at about 9 volts, courtesy of a siries resistor. Hard drives are Barracuda 4's. CPU is stock XP1700. No other fans. Temps are a little high, but OK. Noise level is quite low.

[Bluefront]

Welcome to SPCR.... Ducting an Alpha straight out the side (either blowing or sucking) is an easy mod. What makes my setup superior (IMHO) is the noise factor. This is SPCR you know. Fan openings in the rear are always quieter than any other location. I never used the AMD versions of the Alpha, so I cannot comment on that subject.

[Bill Dunsmore]

Yes, I agree. With my setup it is necessary to have the PC on your left. Also, you probably wouldn't want to cut a blowhole if you have a window.
I think the Alpha heatsinks, which were considered the best available a couple of years ago, are still top performers when low RPM fans are used.
Thanks for the welcome. Just sharing my experiences after reading this website for a few years. Additional observations, mostly just reinforcing what others have said:
(1) Aluminum cases are definitely a waste of money unless you want light weight, not silence.
(2) Lining the interior of the case with Dynamat doesn't do much if you already have quiet components inside.
(3) You might take a look at the new Coolermaster Centurion 5 cases. The front bezel is wire mesh, completely open to air flow. I have modded my case similarly, using wire mesh "IN tray" cuttings. Some form of indirect air flow, maybe up through the bottom of the case, might result in slightly lower noise. However, the open-ness of my case allows for very low fan-induced air flow noise while still having adequate cooling. I use my PC as a home theater rig and it seems quiet to me. On the subject of the new Coolermaster cases, Newegg has them with a 350 watt power supply for about 100 bucks. I hope one of the experts here will investigate that power supply. As a retired EE with time on his hands, I am thinking of buying one even though I don't need it. Comments welcomed.

[RaNDoMMAI]

what were your temps before? or did you not have your 2.4 set up before?

Can you post someting maybe in silent front thread with all your mods to this case and set. like cliffs notes with links to these threads.

thx Bluefront, your projects are good readings.
~RaNDoM

[Bluefront]

When this dbox project is finished I'll post write-up on the whole thing. I tried a bunch of different concepts on this thing and so far it has been a success. I am having a problem with the MB however....it will not run my AIW 9600 video card. I didn't find this out till the whole thing was almost finished (I was using the on-board graphics). Total bummer.

I've got another board of similar size that should work, but that'll take more time. Plus I'm not sure if my Alpha will fit this board. Still thinking about what to do.

I have no before temps as this was a new project. But I have tried the duct setup before. How cool you want the CPU to run, depends on the speed of the fan. Right now I have it maxing out about 1500rpm.....it's very quiet and plenty cool at this speed. If I run my Prescott at that same rpm, it's about 8-9C hotter.

Thanks for the kind words.

Photo album of the dbox so far.

[Wedge]

Blue, is the AIW card made by Asus?

[Bluefront]

No, it's a real ATI card. The board for some reason only supports certain cards....I saw "Radeon 9600" on the list and assumed the AIW would work.

[NARC]

Is your PSU pushed that far back to muffle outlet noise? I assume that eliminates the possibility of using the top two 5 1/4 bays as well.

Ohhhh, now I see why you did it - you've got no room for the inlet because of the ducting. You need a PSU that's open only from the back to make that work without moving it.

Patent Pending? Cool! Very neat mod.

[Wedge]

I hereby dub thee sir Mod of modders.

[Bluefront]

Here's another view of this same duct installed on an A-Open board in a Lanboy case. You can see what I did at the bottom flange of the duct to increase airflow over the north-bridge.

For all you non-believers out there....I know you're out there...here's a partial list of benefits you get with this simple mod.

1. You get one of the better performing heatsinks is its' stock form.....then you make it better by increasing the size of the fan from 80mm to 92mm, and improve the airflow by removing the partially restrictive stock Alpha shroud.

2. You eliminate one fan in your computer. The rear case fan takes its' place.

3. You dramatically reduce the amount of heat going through your PSU, which probably will keep the PSU fan at minimum speed.

4. You get a top-performing heatsink with the most secure mounting method, without the danger of installing a super-heavy tower type heatsink.

5. You get a nice-looking duct without any extensive modifications, that looks store-bought, and not made out of cardboard....it fits perfectly.

6. You get the ability to fan cool the northbridge heatsink without a whiny small fan.

7. There are other benefits......but the best benefit here is the ability to cool any current CPU (even Prescotts) without an expensive, heavy, noisy HSF. It's quieter.

Here's a photo of the duct installed in a case with a bottom-fan PSU in the normal position.




Yeah when you re-locate the PSU rearward to get better airflow to the PSU fan, you cannot use long devices in the two upper bays. I have a fan controller in the top bay, and a floppy in the second bay. And that PSU mod does greatly reduce the PSU fan noise.

[Wedge]

Blue, 2 questions:

1. What is it about the Alpha that makes it cool so well in "suck" mode?

2. Which 90mm fan are you using such that the rpms can be monitored? (sorry if you mentioned this much and I missed it in my reading)

[Bluefront]

Wedge I can only guess at that. I think the mount method may have something to do with it. Similar pin-fin heatsinks use the stock Intel mount bracket, which IMHO restricts airflow over the bottom(hottest) part of the heatsink. The Alpha has no restriction over the lower part of the pins. It's an airflow technique that Alpha has worked at and refined with the 8952 model. Blowing all the CPU heat right out the back of the case before it gets a chance to recirculate in the computer, provides a dramatic temperature reduction to everything else in the case. Unfortunately, there are very few examples of this setup around. Most of the ones I've seen look like crap....cobbed together pieces of cardboard.

The 92mm fan I'm using in this dbox, is a "Colorful" brand temp controlled, from CompUSA. It could go up to 2800rpm, but usually stays around 1400, maxes around 1500. With a Prescott the rpms go up somewhat, but the fan setup is still very quiet.

[Wedge]

I am curious about the temps as I'm sure most of us are, but I have to tell ya that I'm already sold. Looks like PC build #3 for me will be a rendition of this. I totally dig the have-one-less-fan idea, especially if it can keep the CPU temps as healthy as they would be otherwise.

[engseng]

That duct is a great idea, I might implement it one day. However, in that picture it looks like it almosts covers the PSU intake. And since the PSU is primarily the exhaust of the casing, that doesn't look so good.

[Bluefront]

That last photo is deceiving...the duct doesn't rest against the PSU fan. There is clearance there, maybe 1/4" on the one close section. That's a 92mm PSU fan.

Remember the PSU isn't pulling in hot air from the CPU, so you need less airflow through it to keep it cool (lower fan speed, less need for high airflow).

Also the rear case fan is still working normally.....it's still blowing out case air. It's just the air is now routed directly through the CPU heatsink first. You won't have any PSU problems with this mod. I moved my PSU further back (see the first photo) primarily for noise control, and secondly for a slightly better airflow. But it's not necessary to do this. Also a PSU with a rear fan or just a rear opening, avoids this concern.

[Gxcad]

hey blue, curious is the fan at the back of the case or the top of the alpha? Can it be placed at the top of the alpha to increase the distance of the fan noise from the back of the case (and maybe even foam up the inside of the duct to reduce reflections to minimize noise escaping?)

Interesting mod! I does look somewhat professional

-Ken

[Bluefront]

The 92mm fan is on the case end of the duct. It could not be mounted on the Alpha end....too big. You could somehow attach an 80mm fan on the Alpha end, without the Alpha shroud. That would fit in the duct. But I think this setup has better airflow (the fan is not impeded by the pin-fins), and is very quiet.

I made a simple muffler which I attached to the outside of the case. This seems to focus the noise, making the fan hard to hear untill you get exactly behind it. It's amazingly effective.