Silencing a noisy fan, part 2

In Part One, you saw how my efforts to silence a tiny, siren-like fan in my new PC were foiled by a premature motherboard death.

It may be hubris, but I really don't think anything I did harmed the motherboard. Everything I'd done, I'd done before many times without trouble. And that particular motherboard was a relatively inexpensive one with some known burn-in problems. So, if only to preserve my pride, I'll choose to believe that the problem wasn't with my work. 8-)

But my judgment is another matter: I probably shouldn't have cheaped out in making that initial choice of motherboard. So in shopping for a new motherboard, I moved up the product stream a bit to this:


(As usual, click these images for a larger version.)

I still had a high-quality CPU from the dead motherboard, and although I had no way to test it, my theory was that the CPU (and everything else) was fine, and that only the motherboard itself had failed.

So I bought a base (no CPU) XFX 780i motherboard. I liked its features:

(PS: the above image was shamelessly stolen from Newegg.com, one of my favorite online electronics retailers.)

I especially liked that motherboards's approach to cooling.

Here's an end-on view of the motherboard:


And here's the built-in passive (fanless!) cooling system, here outlined in yellow:

The motherboard uses a series of large heat sinks and radiators interconnected with passive heat pipes to move heat around to where it can be dumped into the air.

Here's the earlier plan view with the same yellow outline of the passive motherboard cooling system.


This motherboard comes as a very complete kit:



Note the small box at the lower right. It's a small optional fan that can sit atop the largest motherboard heat sink for extra cooling, if needed. But I wanted to see if I could keep things cool without adding any small, high-speed fans to the box.

Below: A vertical view of the CPU socket. To the right, you can see the largest passive motherboard heat sink and radiator. It's connected via a silver heat pipe to another, smaller heat sink and radiator towards the bottom of the photo.



The CPU carrier is protected by a plastic shipping plate. Removing the plate exposes the socket.



The CPU carrier is a clamping device that holds the CPU in the socket. Here, I've raised the clamping lever:



Here's a side view of the same thing. This also gives you a good view of the passive heat sinks and radiators:



I dropped in the CPU I salvaged from the dead motherboard. It fell into place effortlessly, as it should:



This is the CPU, by the way: An Intel Core 2 Quad. It's actually four separate and interconnected CPUs in one integrated unit (hence the "quad" designation) . All four CPU subunits operate at 2.66 GHz.



With the CPU in place and the clamping lever engaged, I gooped on some thermal grease and then spread it very, very thin:



The enlargement (below) shows the viscous thermal grease spread so thin that you can see the marks left by individual ridges in my fingerprints. The bare metal of the top of the CPU peeks through the "valleys" in the grease. That's just what you want: the grease will be smooshed to a very thin uniform layer when the CPU heat sink is attached. You want the thermal grease just thick enough to fill any imperfections in the mating surfaces of the CPU and its heat sink, and no more.



Because I was springing for a new motherboard, I figured whatthehell: I also replaced the CPU heat sink and fan.

The CPU fan and heat sink on the earlier now-dead motherboard had been OK, but only just. It wasn't silent or even particularly quiet. But the screaming motherboard fans in that unit had made replacing the CPU fan a lower priority.

I now had what I hoped would be a motherboard that would require no noisy, high-speed fans at all, so the noise of the CPU cooler would be more prominent. So, I bought this beast:



It's an unusual axial-flow design. Most conventional CPU coolers blow air vertically. They work, but bathe the motherboard in the waste heat produced by the CPU. In contrast, axial flow means the warmed air exiting the copper heat sink fins can be vented directly towards the power supply fan and out the case without blowing on the motherboard. The heavy-duty components inside a power supply are far less sensitive to heat than the delicate electronics of a motherboard, so I liked the axial-flow concept.

I've used Zalman cooling components before, and like them a lot. They're well engineered and well made. Look at the mirror finish on the bottom of the heat sink, for example (below). Remember how we talked about the better the contact between the heat sink and the CPU, the better the heat transfer? A surface ground and polished flat is optimal for maximizing contact.

Also (above) note how the heart of this cooler is a series of looping heat pipes that run through the heat sink and carry heat to the copper fins, where it can be dumped into the air flowing through. Most standard CPU coolers use only conduction to get heat out to the fins. The heat pipes here should help ensure that heats gets out of the CPU as rapidly as possible, which is just what you want.

Plus, Zalman's specialty is *quiet* cooling; that's how the company got its start. Their fans are engineered and application-specific to move large amounts of air with a minimum of fan noise and turbulence.

Here's the cooler assembly mounted atop the CPU:



And here (below) is a closeup of the base:



I really like how Zalman pays attention to the little details. For example, their mounting system is excellent. The black plastic pieces you see above form half of the mount, and clamp the cooler to the top of the CPU with surprising force. This maximizes heat transfer.

The other half of the mount is invisible in that photo because it's on the underside of the motherboard: It's a large backing plate. This distributes the considerable weight of the cooler over a large area, and ensures that the forces of the heavy spring action holding the heat sink to the CPU don't deform or flex the motherboard. It's all very well-engineered, and a pleasure to work with.

Here's a view from the side of the cooler that will face the power supply. The loops of heat pipe are clearly visible.



In the photo below, you can see the relationship between the CPU cooler and the motherboard's triangular passive heat sink and radiator, to its right. The CPU cooler's fan will draw air through the passive motherboard radiator, too, helping to keep everything cool without adding the optional fan to the motherboard.



Here (below) it's all back in the case, and I'm getting ready to wrap things up.


I used the same large, ganged fans I'd zip-tied together for the previous motherboard:



I made a little zip-tie hinge for one side of the fans:



That way, if I need full access to the motherboard at some point in the future. I can snip one of the simple looped zip-ties on the other side of the fans and rotate the whole fan assembly out of the way.



Oops, almost forgot. The above photo also shows a small system/case fan to the left of the CPU cooler. The PC case originally came with a standard system fan, which is to say a cheap, noisy one. I had another small, quiet Zalman case fan ($8 or so) from previous cooling project, and used that instead.

As you can see below, everything spun up fine.



And I do mean fine. I put the system though another long maxed-out burn in, and it ran perfectly. Windows recognized that it was running on a different motherboard, so I had to reactivate the OS; that wasn't a problem. And, of course, I had to load drivers for this specific motherboard after Windows initially started with generic drivers. The new motherboard came with a driver CD, so this was no problem.

This system is *very* well-cooled. For example, image manipulation is a fairly CPU-intensive task; one that can drive up system temps as the CPU works hard to manipulate the millions of pixels in a hi-res photo. After processing all the photos for this blog post--- resizing them for the web; adjusting color, contrast and clarity; doing some crops and rotations--- this was how the system fared:



For our metric friends, I apologize for the Fahrenheit scale: All the significant temps shown above are in the vicinity of 38C or so. In short: This is a very well-cooled system!

And: Literally whisper-quiet. You can hear a gentle white-noise whooosh, but there is absolutely no mosquito-like or hair-dryer-like component to the sound. It's not a silent system (that can be done, but it's very expensive). But this *is* a blessedly library-quiet system, and one I can sit beside all day without annoyance.

Yes, this was a larger project because I had to replace the motherboard that got fried in the December ice storm here; and then a second motherboard that died a premature death. But the actual replacing of the fans themselves was minor work with a big payoff.

Remember: you don't have to live with excessive fan noise in your PC!