The PA120 series was concieved after the design-success of the PA160. During development of the PA160 it was discovered that radiators could be more finely tuned for the needs of today's watercooling community, where silence has started to become a major priority. Testing and comparison of the PA160 led to a starting point for PA120 series development. A large portion of the initial discussion and theoretical work leading to the first prototype was done publicly and can be viewed here at Overclockers.com.au (post #171 onwards - Membership Req'd). After the first prototype was produced, development went private for obvious reasons, but a number of further revised prototypes were then created and tested.
After many months of number crunching and testing the final spec for the PA120 series was decided upon. This final design showed a vast improvement over the HE Series... by a significant margin when it came to silent fans. Additional testing confirmed that this margin applied not only to silent fans but to regular and higher airflow fans, up to a 130cfm (approximately) point.
The final spec was slightly "outside-the-box" when it came to regular Radiator construction, thus weeks of tooling changes ensued before the new series could be commerically released to retail. Which brings us to the present day...
The PA120 radiator series features a dual-row dual-pass 120mm form factor, available in single, double and triple sizes, optimised for the fans of today and putting into practice everything learned about watercooling efficiency and performance over the past 3 years. The PA Series boasts from 10-40% better performance over the HE Series. 10% for the high / noisy airflow end of the fan market, and up to 40% for the low airflow / silence end of the market.
What does this mean to you as an end-user? You can retain the same performance for even less noise, or better performance for the same noise over your current radiator. If at the end of the day performance is all that matters to you and noise is of no concern, the new PA Series still offers significant improvements over the HE series. Alternately if silence is the goal, you can now have that too, but with more cooling performance than ever before!
"Biggest surprise to me was that a PA with the shroud was able to maintain a performance level at 600rpm that all other rads needed 1200rpm to get to. If it comes to low noise, nothing is even close to the PA at this time." - Radiical53 @ XtremeSystems
The PA120 Final Production models are currently undergoing testing to provide technical data for those who require it. As more results are available to us, we will add them to the list below.
Review by HardwareLuxx Magazine, May 2006 - (translated from German to English by the Author)
“The PA is a radiator of superlatives. It’s bigger, stronger and more powerful than all other contendants, but also more expensive, if you take the price for the (very useful) accessoires and the shipping from the UK into account. But what do you get for your money? As you take it out of the package, you can feel that this is something special in your hands. With much love to useful details, completely manufactured in England, comes a matte black, 2.1kg heavy radiator seeking for equivalents. It has mounting holes for fans on both sides, as all other contenders do, but comes with additional holes on the side to optionally mount the rad in the case or to mount the shroud which is sold separately. As a unique feature it also has a bleeding screw on the opposite side of the fittings, a detail formerly known only from car radiators. A useful detail that comes in handy when bleeding a fully mounted loop. It’s also the only model to come with large 3/8” BSP threads which eliminates another narrow point, resulting in the best score for flow restriction of the whole test. Matching fittings can be found directly at Thermochill or the widely available Eheim 1046/1048 inlet adapters can be used as they have the same threads.
Looking further and more closely, the bad painting can be easily spotted. Looking at the net structure, this can be seen as a feature as another restrictive part, thick paint, is missing. The fine copper fins are quite far apart when being compared to what can be seen on the rest of the contendants. This is another optimization by the manufacturer, minimizing restriction for low rpm fans. The missing cooling surface is compensated by an enlarged thickness of the net where the PA shows one of the highest values of the comparison, 42mm to be exact. But where are the other 18mm adding up to the total dimension of 60mm? They’re divided into 2x9mm large chambers to move the fans a little further away from the net, reducing the dead spot below the fan’s motor hub and the sound coming from turbulent flow just below the fan. This is where the formerly mentioned shroud joins the game again. With it, the fans are raised another 30mm above the radiator, furtherly reducing the dead spot. With the neoprene gaskets that are also supplied, the air just has to go through the rad itself, leaving no leak for it to pass other than through the copper fins. Another effect of the gaskets is a decoupling of the fans, furtherly reducing noise production. Performance-wise the shroud does a really nice job, furtherly improving the already great performance of the PA. Like this, the PA can show the same performance with 600rpm fans as the best other rads get from 1200rpm fans. The optimization for low rpm fans is seen again when looking at the other values from our measurements. The difference between in- and outgoing fluid nearly doesn’t change, the outgoing air does only heat up very little when the fans are turned down. As a result, this setup does dramatically reduce noise without losing any performance compared to a competitor.
So, is there a downside? Well, there is. One is the really high price for a fully setup PA (~170€ including shroud, fan grill and shipping), also the paint job does not hold up to the expectation of such a high quality, high price product [this has been resolved as of June 2006 - Marci, Technical Manager]. Also, the huge size is a problem here and there if someone has to fit a PA into a rather small case. The amount of space needed to make it work efficiently is significantly larger than of many other radiators, as there should be some clearance left to other components to provide proper function.
For those how want to run the PA with higher rpm fans, the shroud isn’t really needed and might be a point to save some bucks: We could see a nice performance increase with 600rpm and 900rpm, but at 1200rpm the PA with shroud looses some performance compared to what it was able to without one, maybe as there’s less pressure from the fans due to the bigger distance to the rad. When comparing the measurements with and without the shroud, a difference in outgoing air temps of up to 2.2K can be seen when using the shroud. This is another advantage of the big package, as the PA can really help to cool the inside of the case when set up like this, as the air is not heated up very much and there’s still quite some air flow due to the low restriction design.
With this, the PA gets our total recommendation for all who are seeking for maximum performance with minimum noise, also having a big case to put it into and a well filled wallet. A very well done package that can be used for many different needs, perfectly doing the job, with the only downside being a relatively high price”