Tested - Positive vs. Negative Air Pressure

Testing and Building Computers for PC Gaming: Understanding Air Flow and Cooling

I'm Norm from Tested and Building Computers for PC Gaming, one of my favorite things to do is build high-end gaming PCs. When building a PC, there's one aspect that stresses me out more than any other - having enough LED lights and never having enough light. I want it to be really flashy! However, the thing that trips me up when I'm building a PC is the air flow and cooling system.

The Cooling of a Computer: A Confusing Aspect

When it comes to overclocking, having a high-performance video card in your PC means you need to keep everything properly cooled. This can get confusing, especially when it comes to creating a pressure difference between the intake and exhaust fans. Positive pressure is created by pushing air into the case, while negative pressure is created by pulling air out of the case. Both scenarios have their effects, even if the fans are oriented in the same direction.

Visualizing Air Flow: A Hands-On Approach

Today, we want to visualize and test the effects of positive air pressure versus negative air pressure inside a gaming computer. We'll be using high-speed video to get an idea of how air flows through the system. For our first test, we're going to try negative air pressure again - more air being exhausted than taken in. This is what we see: lots of fog up front from the intake fans, and then the airflow flowing up to the top of the fan as it's getting sucked in quickly.

Testing Negative Air Pressure at Half Speed

For our next test, we're going to try running negative air pressure at half speed. Maybe you want your fans to be a little quieter? We can see that even at half speed, there's still some airflow happening from the front of the case to the back. However, it's not as much as before - fewer logs are being moved through the case.

Losing Power to Fans: A Crucial Test

Our next test is what happens when you lose power to your fans' intake or exhaust. We're going to disable all the exhaust fans and just leave the intakes running. It takes a while, but eventually, we can see all the fog just kind of milling about up there at the top - no hot air being expelled from the system. The same thing happens when you lose power to your intake but keep the exhaust running - there's no circulation happening in the system.

Air Pressure vs. Negative Air Pressure

So, what did our visualization tests show us? Negative air pressure was more effective than positive air pressure at moving air through a piece of equipment. That's why most cases have more fans on top and back, rather than just front and bottom. It seems that negative air pressure is the way to go for efficient cooling.

Experimenting with Fan Configurations

One thing we want to show you today is the effects of using different-sized fans or configuring fan arrays. We're going to start with four fans stacked up vertically - what can be seen here? The airflow from each fan is minimal, and when turned on together, they don't do much of anything at all. However, if we get a bigger fan - like this 200 millimeter fan or this even bigger one - then the airflow increases significantly.

The Quiet Advantage

While it may seem counterintuitive, these big fans are not moving very much air. In fact, according to cubic feet per minute (CFM) measurements, they're still moving lots of air. The key is that they're doing so at a slower RPM, making them quieter and more efficient. It's all about finding the right balance between airflow and noise level.

Old-School Case Fans

Finally, we're going to check out some old-school case fans - these 3,300 rpm fans might seem small compared to modern fans, but they still pack a punch. They do produce some noise, but it's worth it for the increased airflow they provide. So, there you have it - negative air pressure and array configurations are more effective than positive air pressure alone.

Next Time...

That's all for today's experiment in testing air flow and cooling systems. We'll be back next time to continue exploring new techniques and technologies to improve our PCs' performance.