110CFM Laptop Cooler

WhiskeySix

Introduction

I use a Dell Inspiron E1705 with a Nvidia GeForce Go 7800 video card. This is

a great card, but it generates a LOT of heat in a laptop. For this reason (to

reduce heat production) Dell ships the card underclocked with a core clock of

250MHz (down from almost 400MHz in the desktop version of the card). With

stock Dell cooling, the card would idle in the ~60°C range and max out at

almost 80°C under load. Once I realized this, I decided some auxiliary cooling

was in order.

I tried a Bytec laptop cooler, but was quite disappointed. The problem with it,

as with most generic laptop coolers, is that it just blows air around the base

of the laptop. What I wanted was something to blow cool air into the intakes

for each fan. The GPU and CPU fans are located towards the back of the

laptop, with the GPU being on the right side and CPU on the left (when right-

side-up). The both are centrifugal fans that pull air in from above and below

and blow it out the back of the laptop:

So to increase the air-flow, I decided to implement something like a cold-air

and/or ram-air intake on a car. I did this using a 120mm fan to blow air

through 3" PVC routed directly to the intakes:

With around $40 in parts, I was able to increase my GPU clock speed by

almost 50% to over 370MHz!! What follows is directions on how do create this

cooler yourself. If you're having heat problems with your laptop or want to

explore overclocking*, give it a try!

What You Will Need

(1x) 120mm fan - I highly recommend the 9-bladedSliverstone FM121. It comes with a fan-speed control knob included, has variable output between 38CFM and 110CFM (plus it's all white)

(1x) 3" x 24" PVC Pipe - HomeDepot sells PVC pipe in 2 foot lengths for a few dollars

(2x) 3" PVC "T-Hub" connectors - These have a short rise on the perpendicular branch of the split.

(1x) 4"-to-3" 90° connector

(1x) 12v, 0.5A DC Power Supply - I happened to have a few of these lying around, but you can get them cheap at any RadioShack. (The connector on the end doesn't matter because we'll end up cutting it off anyway)

(1x) Plastic Shopping Bag

(12x) 4" zipties (white)

Wire cutters

Drill with a various sized bits

Pliers

Non-conductive tape

Step 1: Mount the Fan

The first thing to do is lay the 4"-3" bend piece on it's side. In addition to

holding the fan, the 90° bend works like a kick-stand to keep the base flat.

Center the fan on the opening and drill four holes into the to the sides of the

opening. From the inside, insert a ziptie into each hole so that the 'nut' of the

ziptie is inside. After checking to verify that the output of the fan will

blow into the tube, run the 'pointy end' of each ziptie through the mounting

hole and attach the 'nut' from another ziptie. The ties I was using weren't

holding well, so I ended up using two for each corner:

Step 2: Connect the Power Supply

- Drill a hole in the inside-bend of the 4"-3" bend pipe.

- Cut the tip off of your [unplugged] DC Power Supply, and then run the wire

through the hole.

- Cut the adapter off of the power-wire for the fan and splice it together with

the supply wire. (red to red, black to black, then wrap with electrical tape.)

- Tie a simple knot in the end of the joined wire to prevent it from coming

back out through the hole we just drilled.

Step 3: Install the Fan Controller

This SilverStone fan is variable speed and comes with a nifty little knob

controller. The first thing to do is to remove the knob from it's panel - once

you pop the knob off, there's a nut holding the actual controller in place. This

will likely require pliers or a wrench to remove.

Next, you'll need to drill a hole in the outer wall, opposite the power-supply

hole. You'll need to move the drill around in order to flair the hole enough so

that the nut gets a bite on the threads the outside of the tube:

Once you have the knob installed, you need to deal with the wire. The fan-kit

allows for the knob to be 3ft. from the fan, but here it's only a few inches so

there's a lot of extra wire. You can either gather and tape it to the side as

shown above, or just cut out the middle portion of the wire and splice it back

together (which is what I did).

Step 4: Prepare the Base

Now we're ready to start building the PVC base. First thing to do is measure

and cut the 3"x24" pipe to fit your laptop. As shown above, you want the

outside of the exhaust ports to be over (under really) the intakes of your

laptop. (be sure to account for the overlap between T-Hubs and pipe when

before cutting. Once you have the center pipe cut to length, connect all three

pieces, and level them (put them face down on the table so that the openings

are on the same plane):

Step 5: Plug End of the Base

There's a million different ways one could do this, but I decided to use a white

plastic shopping bag wrapped over a small scrap of PVC... works like a drum

head, and forces all 110CFM of air up towards the laptop.

Step 6: Orient the Base

Before connecting the fan, the base must be placed under the laptop to

establish the proper angle.

In this configuration, the base has a tendency to roll forward or back. This rolling will be stopped once we attach the 90° fan connector.

Step 7: Connect the Fan Assembly

Once the Laptop is stable on top of the base, slide on the Fan Assembly. This

will act like an outrigger to balance the whole system:

Step 8: Enjoy Your New Cool Laptop!

(My desk is a little cramped, so I ended up pointing the fan shroud down towards the floor - as you can see in the photo on the left. This did make the base a little less stable than when it was on the desk, but this was solved using a couple of pieces of foam to give the front of the laptop some traction)

Notes:

The pressure is so high when it's at full blast that it overwhelms the

built-in fans - air actually blows out the side and top intakes for each

fan. To mitigate this, I just added some scotch tape over those inlets

so that all the flow is redirected over the heatsink in by the rear exhaust port.

The PVC should fit together well enough that no adhesive is necessary

If you don't have CPU heating problems, the end-plug barrier

(shopping bag in this instance) can be placedbetween the T-Hubs, so that ALL of the air goes to the GPU heatsink)

Results:

As I mentioned above, this mod let me increase my videocard speed from 250MHz to

over 370MHz. Not only that but my max temperature actually droppedunder load. At

250 MHz, without the cooler, the GPU temperature peaked at nearly 80°C. At 370MHz, withthe cooler, I peak at 68°C!

In game (BF2), this clock boost translated linearly to almost a 50% increase in

average frame rate. Using FRAPS to log my framerate every few seconds, I saw my

average increase from ~50FPS to around 75FPS!

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