A short lead in here, some have theorized that the 9.5mm reduction in fan spacing is going to change performance enough to be noticeable. I’ve been of the opinion that the change from 24.5mm to 15mm will change the C/W but a negligible difference at best. Well, we finally get to see how the two theories pan out.
Here is the main chart for bringing all of the logged data in and using this data to calculate Water Avg-Air In, and C/W. Another column you see in the table is Air Capacity Used, this column shows the rise in air temperature relative to the water temperature. Another way to look at Air Capacity used is a measure of efficiency, how efficient is the radiator at moving the heat load from the water running through the tubes to the air passing through the radiator. For reference, click here for the original PA120.3 data table and compare the numbers for yourself.
We did not run into any problems with water temperatures reaching my safety shutoff, which is always a good thing. We have the full 12 tests and corresponding data to in the mix.
Bear with me here, as I just cover the data and chart explanation… its required.
With the data chart above we get to use all those mystifying numbers to build the charts that follow, hopefully these charts put the data into a form that makes sense to the majority of you reading the review. The chart below plots the Water Avg-Air In Temperature or Delta versus the Heat Load applied. This chart is the most useful in estimating the Delta for a given heat load (watts) to be applied to the radiator. Simply locate the wattage on the X axis and move up to find the Delta for a given fan speed. Add this delta to your ambient temperature, and that is what you can expect for a loop water temperature.
For information on calculating heat load for your loop here are two resources I have used in the past. Another method I have used in the past is to Google search TDP for a specific component, that should also help in estimating the heat load that will be in the loop for a specific component. The primary one for me is linked below, they take a lot of the google searching out of the equation and break everything down to just the numbers you need.
Please remember, calculating the power consumption and using that as heat load is not exact and is only an estimate. This estimate will be higher than actual heat load applied as you do transfer some heat to the air circulating in your case around the components. How much difference I cannot begin to speculate, but I just want to state that it is only an estimate and not an exact specification.
Now that we have looked at the plotted results, lets apply the C/W results with a given Delta (Water Avg-Air In) to find how much wattage can the radiator dissipate. Below is the data table for calculations of Deltas of 15º, 10º, 5º and 2º. Here is my classifications for those deltas.
Here are the plotted C/W results over the fan RPM range, as you can see the results do follow close to a plotted trendline. This trendline might not mean much to you, but to me the trend line helps me see that my testing and resultant data are accurate. Additionally, if you plan on running your fans at a speed other than the ones I tested here is another reference point to estimate the results you will see. There have to be some of you out there that geek out for C/W, come on I know you’re out there…
With the C/W calculated, we can apply a specified wattage to give us the watts dissipated for our RPM range. This chart is just the plotted results for a 10º Delta or Average Performance from the data table in the beginning of this section. I have the say the ThermoChill PA120.3 still performs very well across all fan speed ranges and can easily handle a packed loop and maintain a 10C delta.
Moving on to the plotted results for a 5º Delta or High Performance from the data table in the beginning of this section. If you’re following along with your Heat Dissipation slide rules, you’ll notice that a 5ºC Delta can easily apply to a CPU only loop on the low RPM side and scale up quite well as we increase fan speed.
Now here we have the plotted results for a 2º Delta or Ultra Performance. This chart is included purely to show what wattages and fan speeds you need to achieve close to ambient water temps. A 2º Delta is rather tough to achieve with any radiator, exception being the GTX360 at ear bleeding fan speeds. Ultimately you have to make a choice of Delta, Noise, or Wattage of the loop. Closing out the thermal charts with a 2º Delta.
With all of the numbers and charts, you can make your own conclusion on whether the difference between the original 24.5mm PA and the new 15mm… on to the market pricing and conclusion.