Bill Leggett just did a great article about case ducting that showed a genuine temperature and noise reduction. I've been working on a similar ducting project for a while, and the results have been absolutely amazing.

I bought a new case to replace my 1997 overly-cramped box that used those annoying drive brackets. The new case is nice & roomy and has great ventilation. Unfortunately, I encountered the classic modder's dilemma:

"Should I mod my brand new case to include the improvements of the old one, or just bear the slowness of 'stock' speeds for a while?"

For me, this was a difficult choice. Below is a goodbye picture of the old case as I was taking everything apart:

It was an Athlon 2500+ @ 3200+ with a Swiftech block, 1986 Chevette heater core and Eheim 1250 pump - all ˝" internal flow. This water-based mod was awesome at being ultra-quiet and ran very cool. Again, the downside was the lack of space and inconvenient features of the case.

For the new case, I bought a surprisingly great air-cooled heatsink. I also added a 9800XT to replace my 9800nonPro and threw in a gigabit Ethernet card as well. Yea Newegg!

Once the box was running, the CPU temps were great. Then, the all of the temperatures started climbing… for an hour or so - I started getting nervous.

The case temp finally leveled out at about 35ºC (ambient 26ºC) with the case door closed. The processor was running at 67ºC and all of the motherboard power and chipset components were nearly untouchable. The new video card was also cooking. The case fans were definitely blowing out hot air, but my system temps were terrible. I almost made the call to start cutting up the case, but I thought I'd try a few non-destructive ideas first.

I Photoshop'd a picture of the apparent heat problem in my case. Though I had a good heatsink, the temps within the case were already nearly 10ºC over ambient. The case fans were sucking out hot air, but the case has so much hot air that it never made much of a dent.

The cool air comes in at the front of the case and gets mixed with the warm air in the case. Directing a 120 mm fan at the video card brought the GPU temperatures down a few degrees, but not much. I definitely needed something more effective. You can see the thermocouple at the base of the CPU heatsink starting to cry:

Working in a Lab for a few years, I got to see some great machines and innovative cooling techniques for high-powered equipment. One of the guys I worked with designed very high-powered water-cooled electromagnets. The guy was a wealth of information about air and water cooling techniques.

His greatest lesson was about "Volume vs Flow". The key principle in cooling something is to have as small a cooling Volume as possible and as great a cooling Flow as you can manage. By limiting the volume of cooling fluid (air or water), you concentrate the coolant on the hot stuff.

In a big roomy case, the "fresh air" is already warm by the time it gets to the heatsink, then gets recycled around the CPU a couple times while waiting for the case fans to suck it out.

Bill Leggett's article shows a way to use ductwork to bring cool air directly to the hot parts & increase the cooling efficiency. This works well for cooling those parts.

The downside of bringing air in this way is two-fold:

1. The hot air is still in the case (cooking the video, drives, chipset, etc), and
2. The power supply is the only way for the heat to get out.

It's clear that Bill did a great job & the price was right, but I'd be afraid to leave the box on in a warm room. This explains the increased power supply temps.