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:
- Thermal Sensor logging: Crystalfontz CFA-633, logs up to 32 temperature probes and up to 4 fan channels: http://www.crystalfontz.com/products/633/index.html
- 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 insulation cut to fit.
- Tubing is 3/8″ ID x 1/2″ OD tubing. Koolance 3/8″ barbs are also used as the test standard for thermal testing.
- 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 Alphacool ST30 is an exemplary performer at slow speed fan operations below 1000RPM and still manages above average and like 45mm thickness performance at mid speeds in the 1400 RPM range. At 2200RPM the rad still does ok, but falling a bit below average where the thicker counterparts retain performance better. While I’m not too surprised by this considering the XT45 just edged out the UT60 as super slow speeds, I didn’t quite expect it to take the lead at 600RPM. The copper core construction and fin density is making the ST30 my new 600RPM king in thermal performance. Granted the differences at that end are very small and dismal in heat dissipation compared to higher speeds, it is an exemplary performer at slow speeds…excellent!!


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