XSPC Dual DDC Top
Preview
Intro
We recently got our hands on a pre-release XSPC Dual DDC Top, so what better to do than give all of you a short preview. No, this won't be a no info photo session...when we do a preview we want you to see some performance numbers as well. Before you get ahead of yourself now lets get some things straight. Pump top reviews do include a look at pumping performance yes, if you're expecting temperature data in a pump or pump top review well you've just done flipped your lid.
I've been a long time D5 owner and only recently started to enjoy the humm of the DDC--one turned into 3 real fast let me tell you--and of the things I've always seen thrown around is running dual DDC's in a loop. Well, there is a certain community member who never finishes a build and uses zip ties instead of fan screws who requires dual DDC's for his CPU loop. XSPC makes many a DDC accessories, if you don't know what an XSPC Reservoir Top is...well you've probably stumbled into skinnee labs by accident. XSPC is well known for producing the top performing DDC tops along with DDC bay reservoirs and the crazy dual DDC bay reservoir that has two DDC's and two loops, let us not forget the XSPC DDC Reservoir Top.
Ok, with the short intro out of the way lets move on and finally get a glimpse of the beast coming soon from XSPC.<br>
Initial looks...
Its usually at this point of the show that I start going over all the little features of the specimen on the table... slight problem here, its a pump top, so its a very short list of features and this is a preview so very little info has been circulating. It looks as XSPC didn't go radical with G3/8 or change up the screws either, the top comes G1/4 standard and uses the same tried and true M4 shoulder bolts. In case you want to spotlight your dual DDC beast, you've got 2 LED plugs waiting and ready.
A shot of the caboose gives a great perspective on the layout of the dual top. XSPC decided to have the inlet and outlet on the same plane, so there is some difference from XSPC's prize winning single DDC standard and Reservoir tops. The top itself is thicker than your standard top, measuring in at 126mm x 72mm x 25mm (LxWxH). The extra height is used for the horizontal inlet to the top center of the impeller. The best my eyes (holding an XSPC standard top against the dual) standard and caliper can tell, the pump heads are almost identical. The one design choice that really stands out is the triple elbow or U feeding the second pump, I haven't run DDC's in series yet due to the power supply issue (you'll hear about it later in the Test Setup and Methodology section) so I don't know if the Dual Top or two standard tops looped with pump 1 direct feeding pump 2 would win the PQ drag race. The triple elbow does come with a possibly unplanned design feature, a front site-glass of the flow between pumps. I didn't think anything of it until BlueAqua pointed it out during a Skype chat, fill those LED plugs and I bet backlighting the site glass looks pretty good.
Performance Results Intro
P/Q Curves
The legendary Martin has the best explanation on pump curves and how to decipher the results, and most of the following information comes from his site, I paraphrased a portion of the explanation from the legend.
Pump Curves or P/Q (P is pressure, Q is flow) curves are derived from two measurements, flow and pressure, and the P/Q curve is just a visual representation of the relationship between flow and pressure. For the curve, maximum flow rate (GPM, LPM, LPH) is the X axis and Pressure (PSI, kPa, mH2O, ftH20, mBar) is the Y axis.
Almost every pump specification I have ever seen comes with a defined maximum head (or lift) and maximum flow rate. Problem with these curves is they are based on perfect world conditions, where no restriction or resistance are factored into the data and resulting P/Q curve. The key for testing is setting up a test fixture to collect data for all capable ranges of the pump and top in order to develop a real world P/Q which uses the common components in a PC Liquid Cooling System, and that is exactly my goal for each Pump and Top test performed in the lab, we aim for real world scenarios and the resulting data.
One other item to note on P/Q curves is the Trendlines used on the scatter plots. DDC's trendline has a best fit polynomial using a 3rd Order, where as D5's have a best fit with 4th or 5th Order. Now the problem I am running into with Excel is a defect that has been around since Excel 2000 and polynomial trendlines. Sometimes no matter what you do, the trendline will not work on a best fit, the code inside Excel is not consistent. As a result, some of the trendlines you see on the individual test reports will not represent the proper trendline. Additionally, I did not forecast or predict ahead on the compiled P/Q curves for all results, some did not have the Excel bug and some did.
Dynamic Head Pressure
In short, dynamic head pressure is the pressure measurement at the outlet minus the pressure at the inlet or the differential. Dynamic head pressure is a better measurement for the actual pressure the blocks will see in the loop. Many other pump tests have only measured the outlet pressure, which does not take into account the inlet pressure and does not represent a true pressure measurement for your cooling loop. Dynamic head pressure is quite easy to add to the Pump test fixture and requires a T fitting at the pump inlet and a T fitting at the pump outlet. The pump inlet T is hooked up to the negative side of the manometer and the Outlet T to the positive side of the manometer.
Power Consumption vs. Flow Rate
I took Martin's lead on this measurement and included these in the individual test results that you will find at the bottom of each speed setting graph. For each flow setting the voltage was regulated to 12.00 volts as set on the DC Power Supply and verified on the multimeter hooked up for all tests. In addition, the current (amps) draw was recorded for each flow setting, luckily the DC power supply I have has a display for amp draw, initially I had a multimeter hooked up but as tests went on the two displayed identical readings. As with Martin's tests, the voltage regulation and amp draw data recording is really used for the efficiency charts, but power consumption is displayed on the P/Q curve charts for your reference as well.
Efficiency
No shocker here, another test result that was started by Martin and I only feel that it is right to continue providing the information. The efficiency charts are simply a graphical depiction of the water horsepower to break horsepower of the pump at the given flow rate, showing which flow rate the pump (and pump top) will perform with the best efficiency.
Test Setup and Methodology
The pump testing loop is a completely separate loop on in the lab. In testing the top I had to alter the pump test fixture a bit now that we're powering two pumps instead of just one. The Mastech power supply I have starts to kick in the safety way to early for Amp draw, so I had to snag the Meanwell for the TEC blocks. Problem here is with putting the DMM in series to take the current load, so I did the best I could with what I have and just measured and regulated voltage to 12V. No power consumption or efficiency curves here, just PQ. The pump test loop consisted of King Instruments 7520 Rotameter, 1/2in. brass gate valve for controlling flow of the loops both of which are fitted with 1/2in. NPT 5/8in. ID barbs. Bitspower 1/2" High-Flow fittings are the only fittings used elsewhere for consistency across all of the benches at skinnee labs. I use an assortment of measurement tools for pump testing, here is the list.
- Power: Meanwell S-320-12 (0-12V, 25A +/-1% - R&N 150mV) switching DC Power Supply
- Volt/Amp Measurement: Fluke 23 Series II Digital Multimeter
- Flow: King Instruments 7520 Rotameter 0-5GPM, 10" Scale - Accuracy 2% of scale.
- Pressure: Dwyer Series 490-3 Digital Hydronic Manometer - Accuracy 0.5% of Scale, Range 0-50.00 PSI, Resolution 0.01 PSI
For each configuration tested, the loop was bled and ran for 20 minutes prior to measurements taken. After 20 minutes, power to the pump was shutoff, and the Manometer was reset to zero PSI. This step ensures a proper measurement of the total dynamic pressure for the pump is recorded. With the power supply back on and another 5 minute wait time, the tests can begin. During the test runs, Voltage is adjusted to 12.00 volts in order to achieve a constant voltage across all tests, voltage was verified prior to the 2 minute runtime and verified before measurements were recorded. Also to eliminate and pressure variation, each flow setting was , given a 2 minute runtime before measurements were recorded. For each flow setting the PSI, Voltage and Amperage are recorded. Except no amperage recording this time.
Test Results
By this point of the preview you're already saying to yourself enough scrolling and text, where is the compiled data and charts...well, I won't delay any longer. Remember, no amp draw numbers were measured and the gray areas on the data table below represent the amp draw and calc's that are use amps for each set 0.25GPM interval.
Yeah-yeah a bunch of numbers, but what are the gains from adding a second DDC to the loop. Well, the XSPC top we have on the bench shows some rather nice scaling across the PQ curve. In the next two charts I have included the previously unreleased--by unreleased I mean my lazy butt hasn't written the review yet--XSPC V3 DDC Top PQ. This added little bonus is only for showing the gains of adding another DDC using the XSPC Dual top. We have plans to test pumps in series, but we have to get this little power supply and amp measurement problem taken care of before we test multiple pumps on the test fixture... monitoring and regulating voltage to 12.00V is a requirement for pump testing at skinnee labs.
We cannot forget our metric system readers, and like always here is the same data just converted to LPH for flow and kPa for pressure. I like kPa versus mH20, plus I think the metric pressure standard is kPa anyhow.
Before anybody gets all rowdy about my not doing a review and releasing data on the XSPC V3 DDC Top, there is a link to just the data and standard PQ charts.
Wrap-up
There ya have it, XSPC is bringing a restriction busting monster to market very soon. I have not heard nor want to speculate on the price you will see once the top starts hitting retailers, but knowing XSPC this will be priced very competitively It is true, the logged data is showing some major Total Dynamic Head gains over a single DDC and I for one did not expect anywhere near the performance scaling. I expected to see a 30-40% TDH gain at the sweet spot of 1.5GPM (roughly 340LPH), but we're seeing a 2x factor here. Yes, 5.31PSI to 10.87PSI. I will state again, I haven't looped up 2 single XSPC V3 Tops in serial yet due to my DC Power Supply problem and not being able to safely measure current draw while testing. Don't fret though, in time I will have the gear required to log current along with voltage to complete the normal tests.
Two things you should really take away from the preview here... One being the scaling of pressure when you run two DDC's in serial, its certainly a larger scale factor than what I anticipated. When you put two pumps in series, you're boosting the PQ curve way up (as seen in the charts above), the restriction of your loop or pressure drop moves further along the X or flow axis...translating into a higher flow rate for your loop. And two, you don't have to get two XSPC standard tops and loop them together with a tube bridge, XSPC brings a top that has inlet and outlet on the same plane and tries to keep the footprint as small as possible.
If you've been like me and on the fence about throwing a bit of caution into the wind with your pumping, quit wasting time and try dual DDC's. The XSPC Dual DDC top certainly opened my eyes to something I was missing out on. Also, interested as to how your blocks are going to perform thanks to the extra shot in the arm? Check out Vapor's extensive look at flow rate scaling compared to block performance. XSPC's Dual DDC beast will be coming to a loop near you very soon!
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Originally Posted by creidiki
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