Homemade Hard drive Cooling

by Karl Haase 2/4/2003 (in progress)

First off, allow me to apologize. I'm only making this webpage as an afterthought, and it is still in progress. As a result, there are not any construction pictures. If i get an opportunity to add some later I will. (legal stuff) If you try any of this and hurt you computer, don't say you weren't warned.

Many people have complained about the excessive noise their PowerMac G4s make, but there is a more subtle problem with the Powermac Case design that is more sinister: poor cooling performance. Essentially, the Yosemite towers are designed to suck cold air in at the top of the case, and blow hot air out of the bottom (although some is vented through the PSU). This method is contrary to the way convection works, as a result lot of warm air is cycled back into the case as it rises from the bottom past the air intake. The net result of this that PowerMac G4s (notably Quicksilvers...) tend to run a little hot. The cases are warm to the touch when they are on, and I have seen exhaust temperatures from my case exceed 40 degrees C (measured with a dry mercury thermometer). This high heat is probably not good for any component in the computer, but it's particularly bad for for hard disks, which are generally comfortable at temperatures less that 55-45 degrees C.

Last October, I acquired a USB 2.0 Hard disk, which I placed on top of the Powermac's Case. The drive and it's case seemed conspicuously warm, but I didn't worry. After about a week of uptime, the new drive had mysteriously lost all of its data. I reformatted the drive, and attached it to another computer, where it operated fine for several weeks. When I placed it on the Mac again, it fried within hours. Another format later, I put it on a shelf high above the macs heat, where it continues to operate flawlessly.

It occured to me that the heat inside the g4 could cause the 2 drives inside the mac (OEM 60 gig Deskstar and a Seagate Barracuda) to do the same thing, but I didn't do anything about it until a sudden failure last December where both internal disks simultaneously lost all of their data as the USB 2.0 Drive did. The Seagate proved unrecoverable, and had to be submitted to seagate with a RMA. Although this could have been an random act of god that caused this, I have my suspicions that the Powermac runs too hot for the comfort of an internal disk drive.

After that little catastrophe, I decided to attempt to avert further heat-related angst by constructing a cooling system for my hard disks. Although I'm sure the solutions on the market now for cooling hard disks work fine, I was on a tight budget, so I used some materials i had laying around and a couple of large heat sinks from OEM Parts in Colorado Springs for a total expenditure of less than 10$.

For the record: My computer is a G4 933 with 768 megs of RAM (1 256 meg and 1 512 meg chip), 2 internal hard drives, SuperDrive (AO4), OrangeMicro USB 2.0/Firewire Card, Apple OEM Ultra SCSI Card, RealTEK NIC, and a Geforce4 Titanium
.

Here you can see the Disk Cooler I made. I took a used 12 volt CPU fan and grafted it on to a large heat sink using nylon ties. I then spliced a inline power tap to the fans 2 supply wires. I wrapped the remaining RPM sense wire inside the heat sink in case I need to use the fan for future projects.
Here's a (blurry) View from the top of the cooler. The cooler is quiet high, so trying to fit it inside a machine with a large PCI card in the bottom slot would be a mistake (crunch!).
Here is the cooler placed on the SCSI drive, held in place by a nylon tie. Beside it is a normal heatsink on the OEM IBM drive. I didn't but a fan on it because of it's proximity to the big case fan and the PCI cards above it. The combined height of the drive and the cooler makes it a little cramped inside the case. The other Cooler is just sitting on the OEM drive at this point because I haven't found a good way to secure it yet. (Click on image for a higher resolution version)

Here's some more close ups of the cooler inside the case. Since installing this, the drives have been noticeably cooler to the touch. Perhaps I will do some tests in the future with a thermocouple gauge and measure the magnitude of the change. These are actually "hot" images... the computer was on when I took them, but the camera's shutter was fast enough that you can't see the fan moving :(
Back to Computer stuff