XSPC RS360 Radiator

Posted: March 27, 2012 in Radiators
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Thermal Testing

I’m using my new V2 radiator test bench for testing which nets significantly lower watts dissipated numbers than my old open air testing.  This new bench is both insulated and shielded from getting any external cooling help and likely more accurately simulates a closed case condition.  The tested parts are as follows:

Test Specifications:

  • Temperature Probes: Dallas Digital One Wire DS18B20 probes.  These are good to about .2C absolute accuracy in normal water cooling temp ranges and have a nice fine .0625C resolution.  Also since they communicate digitally, you can string the power, ground and Vdd wire in series between all the sensors limiting the amount of wires significantly.
  • Pump: Swiftech MCP-35X2 at 40% PWM.  Simulates medium pumping power and results in roughly 1.5GPM +- depending on radiator restriction.
  • Block: Danger Den MC-TDX block
  • Heater: Standard Aquarium 300W Heater with safety switch soldered in the closed position so heat remains on regardless of temperature.  This requires removing the heater element from the glass tube, soldering the two tabs together and putting it all back together.
  • Heater/Reservoir Bath:  I fabricated this from 1″ schedule 40 PVC with a T and elbow to 1/2″NPT threaded fittings and then used NPT nylon barbs to connect tubing.  The cap I had to use a 1-1/4″ threaded cap and turned it in my lathe to fit the exterior of the 1″ T fitting.
  • Insulation was a combination of 1″ and 1/2″ pipe insulationg cut to fit.
  • Tubing is 3/8″ ID x 1/2″ OD tubing.
  • Case Material – 1/2″ x 8″ Pine it’s a little over 24″ wide to barely fit 4x140mm rads.  The bench overall height is about 18″.
  • Inlet port was fabricated from a 4″ flange material making an ID opening of 4.540″ Diameter.  I shaved the threads out of it and tapered the inlet on the lathe for a smoother inlet.
  • Acrylic panels are all .100″ thickness and I dado cut slots into the shelves for them to fit into.
  • Current Fan Controller is a Scythe Kaze Master, fed by a Koolance SPD-24 to slightly overvolt fans to 2200RPM.
  • Heater Control is via a 3A  generic Variac, although 5A would be better for higher heat loads.  I am using the variac to dial in the Watts into the variac to 100W, 200W, and 300W for each RPM.  5Watts is then added for the pump heat minus variac heat, so each test is targeting approximately 105W, 205W, and 305W.
  • For Watt Metering – P3 Kill-A-Watt and just manually observing and correcting wattage is used.  Wattage normally does not vary by more than 2-3 Watts.
  • Fans- Titan Kukri H PWM fans – I picked these fans because they had a good RPM range and I thought would better represent 25mm fan performance over using 38mm fans.  They do have a more dense 9 blade fan design similar to the Gentle Typhoons. I’m not using them because I think they are superior in noise over other fans, I am simply using them because I can run them from about 650RPM clear up to 2200RPM to get a good broad range of RPM levels tested with a single fan type.  They seem like a pretty good fan, but I wouldn’t suggest they are superior over other 25mm fans.
The radiator is initially installed into the radiator cabinet with only the bottom three fans push condition.  The system is filled with distilled water and allowed to bleed and fans allowed to warm up.  Then the variac is turned on to apply heat load and dialed in to 100W and the fans are adjusted to 640RPM.  The Crystalfontz is then used to monitor fan RPMs and adjusted to a good stable level and all 17 of the thermal sensors are also turned on to start recording air in, air out, water in, water out over those 17 sensors and the fan RPM.  All of these are then recorded each second and allowed to run and log temperatures for approximately 1 hour while carefully controlling ambient temperatures.  After about 30minutes the data log is brought into excel and reviewed for stability and ambient results.  After the system reaches stability while ambients are nice and level, the data is saved and trimmed and an average of the stable data is averaged.  This averaging includes the average of the fan rpms at the time of the test as well as all the temperatures.  That data is then copied to the below chart to calculate the results.  At that point the radiator fan speeds are increased to 1400RPM and heat load to 200W and the test is repeated.  Next the fans are increased to 2200RPM and heat increased to 300W and data logged and extracted again.  After push is complete, the pull fans are then added and the three tests are repeated as described above.  The most critical and difficult part of this is maintaining a constant ambient temperature.  It doesn’t have to be any one number, but it needs to hold constant with no more than about .5C rise or fall in any 30minute period.  This is why logging is used to evaluate and continue logging data if needed to collect a good data point.  Simple things like someone opening the front door for a minute will cause a sudden drop in ambient and the test has to be redone.
Here is an example of one of the data points below collected:
Summary of 6 tests:

You might note the “Air. Efficiency” results, while slim in thickness the RS360 is still using up about 71-84% of the air’s available heat capacity.  This volumetric heat capacity of air is the reason why double thickness designs can’t see 100% improvements.  The air only has so much heat storage capability, so having fresh cold air is critical to gain the most out of the cooling fins.

And while this is all fine and dandy, it doesn’t mean much without some sort of comparison, so for now I’m including the RX 360 so you can see the value rad compared to its brother premium double thickness radiator.  I will have more to compare with later after completing more tests.

As you would expect the premium double thickness RX is superior in thermal performance, but with push and push+pull data you can also see than the RS with push+pull outperforms the RX with fans only in push.  You should also note the dramatic change in thermal performance relative to RPM ranging from 75 watts at 500RPM clear up to 375W at 2200RPM.  The single most dramatic factor is fan speed in radiator performance as you might expect.  Not having other data to compare there isn’t much more to say other than these will be excellent baseline radiators to compare subsequent tests.  We have two well-known radiators, one slim/value and one premium/double thickness.  As you can see the difference between slim and double thickness is about 8% or so.

Summary Bar Chart

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