EK-Coolstream RAD XT (360)

Posted: April 16, 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 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 radiator is installed into the radiator cabinet with only the bottom three fans push condition.  The fans are all permanently fixed to the acrylic template below with a foam gasket so the fans are installed, run, and logged exactly the same on each radiator. 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.  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. In a nutshell, I am spending a great deal of effort to review logged data and extending the data logging period as needed to ensure a good stable ambient temperature which results in more time per data point but a much more accurate data point.
Summary of 3 tests:

The XT performed well and was more of an all around performer hanging in there just a hair below most of the premium 60mm thickness radiators with some minor tuning preference toward slower speed fans.  While it is slightly down the list since most of the rads tested are the thicker models, you can see the difference is not much more than 5-10 watts and holding it’s own despite the slightly slimmer 45mm thickness.

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  1. Zareth DeTullio says:

    I’d really like to see some comparisons on thinner radiators between push and push/pull at slow fan speeds.
    The idea being that 6 fans at 800 rpm are often a lot quieter than 3 fans at 1200 rpm and you may be able to get good slow fan speed performance like that.

  2. Badelhas says:

    Hello Martin and congrats on the fine work you do here, thanks a lot.
    I was wondering if it would be possible to test the Asetek 760gc and 740gf clc kits? They look interesting but no one did a review on this yet…


    • Martinm210 says:

      If you have a lead on a parts sponsor let me know. Not having much luck on he kits sponsoring.

      • Badelhas says:

        How about if you say to them that there isn’t a single site or proper reviewer who reviewed their 760gc cpu+gpu watercooling kit? Maybe they will be interested in that. There are some users who done it and the results are surprisingly good for a mere 120mm radiator. I ordered a 760GC and a 740GF to cool my 2500k OCed to 4.3Ghz and my two Inno3D gtx570 Hawk in SLI. I will see if my temps and noise goes down but it will be a rather subjective opinion, if you could do it it would be great so that everyone knows if it’s worth it or not. ;-)

  3. Thomas says:

    I’m looking at this and the XTX for a possible watercooling loop when I step up from the Corsair Hydro H100i to a full custom setup. As I’m going to mount it in the roof of a Corsair Obsidian 750D and possibly do push/pull the XTX might be a bit on the big side. Do you think this one would be enough for a moderately to low overclocked system with just two blocks (GTX 770 gfx card and 4670 cpu). Planning to go for silent run so low rpm fans. Also, am I right in thinking that with the low rpm fan intended design that static pressure isn’t as important as with normal rads?

    • Martinm210 says:

      Sure. I would let static pressure sway you fan choice too much. While there is some difference between fans, I have found that they all produce about the same air flow through a radiator with about a 400rpm difference. Also static pressure is actually a theoretical point when air flow is zero and means less than a fans PQ curve or pressure capabilities at a point along that curve. A fan like the gentle typhoon with lower static pressure but great curve can produce more air on a radiator that some fans with higher static pressure like Cougar fans, etc.

      Basically RPM speed is really the better reliable indicator of air flow performance and the faster the more air. Buy Gentle typhoon AP-15s if you want the lowest noise per speed at 1800, it actually produces more air than most 2000rpm fans at about 10dbA less noise.

      If you want to run <1000 rpm fans, just about any will do, good cheap yate loons or artic cooling F12s are good cheap options that perform well at slow speeds.

      • Thomas says:

        Thank you! quick and extensive answer, you’re a real help to a wc noob :) The fans I’m actually considdering are the Be-Quiet SilentWings 2 or Shadowwings (at least for case fans) all PWM. Any thoughts on the radiator choise as mentioned above? Also need to find a reread your flow/pressure article again for the pump decision (EK DCP 2.2 or 4.0).

        • Martinm210 says:

          EK rads are both good performers. Rad performance is also very close. The all copper Alphacool equivalents pulled very slightly better numbers when measuring very small numbers but not so much that average use will show anything obvious. I think best to worst rad is no more than about a 17% difference so very close regardless of thickness or brand.

          BeQuiets are ok, but only tested about average. Nice looking and lots of accessories, seems like good quality, but not as good a performer as GTs. Haven’t tested the other one, but would guess average performance as well.