Experimentally determining the coldest I can get with air

[JamesWatt]

9. Improving the duct
There were a couple of issues with the last version of the duct.

The rear exhaust fan was blocked. This was because the duct hose wasn’t flexible enough to get from the back of the heat-sink all the way to the exhaust hole. I replaced the duct with more flexible duct.

Not enough air was being drawn in. There was no front intake fan. I added one. The front of the duct was blocked by the 5 ¼” bay grill. I removed it (http://postimage.org/image/brhwh4pw/).

With those fixes, here’s what I got. Both measurements were taken with the front and rear grills removed.

44.9 C (66 C-21.1 C): Silverstone FM121 front intake & rear exhaust
38.2 C (59 C-20.8 C): Duct with Silverstone FM121 front intake & rear exhaust (http://postimage.org/image/br9mse90/)

11. Cooling the northbridge
One concern that was raised with the duct was that the north-bridge would run too hot. To remedy the issue, I tried putting a Rosewill RFA-120-BL on top of the case. Both trials increased the cpu – ambient so much that I decided against the top fan. All trials were done with the duct with Silverstone FM121 front intake & rear exhaust.

38.2 C (59 C-20.8 C): Control
41.2 C (62 C -21.8 C): Top fan set to exhaust
44.3 C (65 C -20.7 C): Top fan set to intake


Future actions
• I am going to pick up a vacuum and a pressure gauge to try to see what the deal is with pressure and temperature.
• I am going to buy some fans with the same CFM, but different static pressures and see how they perform.
• I will try adding some more space between the heat-sink and fan.
• I will try cooling the air before it enters the duct.
• I'll surround the front intake fan with foam for a better seal (thanks LedHed!)