The truth about DDC's

[Waterlogged]

OK, so it's time for the much hyped and anticipated results of my somewhat "extensive" testing of the various DDC's on the market and how they compare to the older DDC-2. There is even a surprise guest in the test results and the only reason I tested it was because I was genuinely curious about it.

Now, before I show the results, I'll go on the record and say that these results are not to be taken as gospel as the methods I employed are not the same as those used by Martinm210 or skinnee (or even Vapor IIRC) but, they are pretty decent and good enough to give a realistic idea of what you can expect. Now that I'm done with the disclaimer, lets get to the testing methods and then the results.

Testing methods:

For flow test, I used a Koolance INS-FM17 attached to CPU fan header on an old MoBo and read the results in bios. Results were rounded to the nearest .1 LPM.

For Pressure test, I used an old fuel pressure gauge that reads 0-15PSI (graduated by .2PSI). It was mounted via push-in fitting to a T and then to the res via a valve. The valve on the res was opened and closed several times to confirm the reading taken. Since the gauge is a bit old, I decided to add in the ± you'll see in the results as wiggle room even though the results were easily repeatable to within .1PSI.



For total lift, I used the old tried and true method of tubing going straight up a wall and measuring the distance the water traveled from the end of the barb. Number's were rounded down to the nearest full inch to keep things a little simpler. I will admit that "me judging height by eye" = epic FAIL as the room I tested this in at work was only 24' and not the 30'+ I originally reported. Good thing I didn't need all of the 24'.

For RPM's, pumps were hooked up to a 3.5" Kaze Master and the most prevalent RPM was recorded with ± wiggle room. For those pumps that changed RPM's due to added restriction when the valve was closed during pressure testing, both a min and max number was recorded.

All the tests were repeated for both the 3.25 and DDC-2 with the Petra top for each respective pump. This was done to show the effect after market tops have on the pumps compared to the stock top. For the other models of DDC's not tested with this top, the results for the 3.25 "should" scale similarly as they would use the same top.

Now, for the results.

Stock Top

Pump__________Total head pressure (PSI)__________Total lift (Foot)__________Max Flow (l/m)__________RPM's

3.1 (new PCB)__________5.4 ±.2____________________12' 2"__________________~7.3_____________3840 ±30

3.1 (old PCB)___________5.4 ±.2____________________12' 2"__________________~7.3_____________3900 ±30

3.2___________________6.8 ±.2____________________16' 1"__________________~8.4_____________4530 ±30

3.25__________________9.0 ±.2____________________21' 9"__________________~8.4____________4650-5340 ±30

DDC-2.________________9.8 ±.2____________________23' 4"__________________~8.4____________4530-5340 ±30

Koolance PMP-300._______3.9 ±.2_____________________9' 9"__________________~7.0____________4500-5640 ±30



Petra Top

Pump__________Total head pressure (PSI)__________Total lift (Foot)__________Max Flow (l/m)__________RPM's


3.25__________________7.8 ±.2____________________19' 1"__________________~9.9____________4320-5220 ±30

DDC-2.________________8.2 ±.2____________________20' 10"________________~11.2____________4290-5430 ±30

As for the questions about the revised PCB and being able to do the solder mod, I really wish I knew more about electronics than I do. I pulled apart a new 3.1 and a 3.25 and the only differences I found were about 10/11 of the flat resistors. The micro controller is the same and I tried several different ways to get a number off the FETs but there was just too much conformal coating on them. I tried to scrape it off and the numbers disappeared as well. The following pics are for anyone out there that is more knowledgeable that may pick up on something that I didn't/couldn't.

(Click for larger images)


As for being able to mod the newer PCB, that's unfortunately still up in the air. Personally, I'm going to say it's not possible as these look to possibly be a simple mod away from being PWM controllable from things floating around in the rumor mill.


I tested the Koolance PMP-300 on a whim as I was a little bit curious about how it performed. While not as good as the "main" pumps such as the DDC or D5, it did exhibit qualities that would make it a nice little pump for a separate MOSFET or Chipset loop with a 80mm, 92mm rad or 120mm. It is reasonably quiet (on par to a MCP350/3.1) and as you can tell from the numbers, has more than enough oomph for a small load loop.



Oh. . .and skinnee, I win.

[BringerOdeath]

The DDC-2 is that old model they no longer make right?? Well, i am happy I bought those 3.25's now!! I wonder how much flow i will get with 3 3.25 pumps with the XSPC triple top!! :P

[Philwong]

I'm confused? The mod tops reduced the head pressure, but yet increased the flow?

Phil

[Kibbler]

Thanks for the effort, those are compelling results. Makes me glad I swapped out my 3.2 for a 3.25 in my build.

For those pumps that change RPM's, both a min and max number was recorded.

Can you explain why the DDC-2 and 3.25 have an RPM range while the other pumps don't?

[Kibbler]

I'm confused? The mod tops reduced the head pressure, but yet increased the flow?

Phil

Pinch a garden hose.

[Waterlogged]

Can you explain why the DDC-2 and 3.25 have an RPM range while the other pumps don't?

Sorry, I should have been a little more clear about that (I'll fix that so it's more clear). As the restriction goes up, so does the RPM's. It has something to do with a RPM limiter in the micro controller on the 3.1's and 3.2's, regardless the RPM, they'll stay within a handful of RPM's of where they were set to run for the amps given. The DDC-2 and 3.25 don't have this limiter and it appears that it's the lack of the limiter is what allows them to really crank out the pressure. You can see this in a prior test I did.

http://img535.imageshack.us/img535/3607/file9751.mp4

The DDC-2 is that old model they no longer make right?? Well, i am happy I bought those 3.25's now!! I wonder how much flow i will get with 3 3.25 pumps with the XSPC triple top!! :P

Yep, the DDC-2 is no more. IIRC, nikhsub1 figured it takes 4 pumps to effectively double a single pump in a loop, so. . .you should get ~2/3 of that. . .give or take a little.

I'm confused? The mod tops reduced the head pressure, but yet increased the flow?

Phil

Although, a couple tops do have a slight increase in max pressure over stock. Most tops however increase max flow rate and the pressure at max flow over the stock top as shown by Martinm210's testing. The one thing you have to remember though is that max pressure is at zero flow.

http://martin.skinneelabs.com/DDC32PumpTopTesting.html

[snoro]

I just have 1 question waterlogged, do you think one ddc3.1 is enough for a cou loop only. I bought two of those to make a 2 loop setup, first loop is xspc res top, ddc 3.1, hk cpu blobk of supreme hf (still not decided which one to get), hw labs gtx360. Second loop is xspc top, ddc3.1, gpu full cover block, hw labs 120 pro compact rad, mosfet block, swiftech 220mcr rad. Does the ddc3.1 can give enough head pressure for those loop ?

[shazza]

Thanks, Waterlogged. Appreciate the effort that went into doing this.

[TadZilla]

Sorry for my n00bishness, but this thread has me curious: Is the Swiftech MCP355 a DDC 3.2? If so, looks like I need to get a 3.25

Thanks!

-TadZilla

[RoadconeTuning]

im curious as to the difference you'd get with a ddc-3.25 vs a DDC-3.1 with a high restriction loop... ive got 5 blocks in mine and 3 of them are fairly restrictive... i wonder if id gain anything with a 3.25 over my current 3.2 due to the runaway rpm

[Petra]

I'm confused? The mod tops reduced the head pressure, but yet increased the flow?

Yes, this is the trade-off with the custom tops (the odd exception being the XSPC reservoir top and a couple other integrated-reservoir tops)... the trick is to go for the least drop in head pressure and the largest increase in mid-range flow. What really confuses most people is when you tell 'em that the max head/discharge numbers aren't very meaningful since the middle 50-65% of the performance curve is all that matters for most PC cooling systems.

Waterlogged: based on some of my old curves, you're looking at, what, about a 3psi drop across that flowmeter given the "max" flowrate numbers you were able to pull?

RoadconeTuning: The higher the pressure drop of the system, the closer the results are going to get between pump configurations (to the point where it really doesn't matter wether you're using a custom top or not...take a CPU/GPU/radiator loop with an AqX MP-1GPU, MP-05 SP LE CPU block, and a BIP, for example: you'd be looking at a flow difference of about 0.07GPM between a DDC-2 with top and without top, a difference of about 0.18GPM between a DDC-2 with top and a D5, and a difference of about 0.11GPM between a D5 and stock DDC-2).

[RoadconeTuning]

so in reality it doesnt matter what we use...

[Petra]

so in reality it doesnt matter what we use...

Considering that the DDC-3.2 doesn't seem to benefit as much from custom tops as the old DDC-2 and it's less powerful overall, pretty much. It's one of the reasons why I never brought my DDCT-02 top project (a complete redesign to replace my DDCT-01 & DDCT-01s tops) to production after my performance analysis of the DDC-3.2 pump.

[Waterlogged]

Waterlogged: based on some of my old curves, you're looking at, what, about a 3psi drop across that flowmeter given the "max" flowrate numbers you were able to pull?

Wish I knew Alex. I did things the hard way as I wanted the purest numbers possible, flow test only had the flow meter in the loop and pressure test only had the gauge in the loop. I suppose I could go back and do that test when I get a little more time. I also have another flow meter (INS-FM15) that I could toss in and check the drop in flow on both my meters as well. . .was something I was planning on doing anyway.

[damha]

I wish you had included some current draw numbers. Looking at the discoloration around the 3.25 center tells you just how much hotter that thing gets over the 3.1. To me hotter = higher failure rate.

[Waterlogged]

I wish you had included some current draw numbers. Looking at the discoloration around the 3.25 center tells you just how much hotter that thing gets over the 3.1. To me hotter = higher failure rate.

I wouldn't put too much stock into the PCB discoloration on DDC's. Both of those pumps look exactly the same when I took them apart prior to testing for a quick inspection. I would have done draw number if the one DMM I have didn't blow it's 10A fuse about 2½ years ago. I've been unable to find a replacement locally and I'm not about to buy another $100 DMM when everything else works on mine, I simply can't afford it. The analog I have only goes to 250m which is useless for these pumps.

[zanzabar]

Considering that the DDC-3.2 doesn't seem to benefit as much from custom tops as the old DDC-2 and it's less powerful overall, pretty much. It's one of the reasons why I never brought my DDCT-02 top project (a complete redesign to replace my DDCT-01 & DDCT-01s tops) to production after my performance analysis of the DDC-3.2 pump.

they do make routing much easier

any chance of a retest to get the numbers for the 3.2 with top, as if there is a rev limiter it should perform differently, and mine stays at 4700 rpm with the ek v1 g3/8 top

[Kurz]

Considering that the DDC-3.2 doesn't seem to benefit as much from custom tops as the old DDC-2 and it's less powerful overall, pretty much. It's one of the reasons why I never brought my DDCT-02 top project (a complete redesign to replace my DDCT-01 & DDCT-01s tops) to production after my performance analysis of the DDC-3.2 pump.

NOW I know the Mystery of the missing DDCT-02!!!

I never got around to asking you Petra.

[Captain H.N.]

Wow, that came sooner than I thought. Do you notice any more noise from the DDC 3.25 compared to the DDC 3.2, since it spins faster?

[skinnee]

Good work WL!!

I knew that PM I recently sent would have some sort of negative recourse. I am done with PQ, just need to finish up this MCR-Stack and will do "average" loop flow rates.

[Waterlogged]

any chance of a retest to get the numbers for the 3.2 with top, as if there is a rev limiter it should perform differently, and mine stays at 4700 rpm with the ek v1 g3/8 top

Sure thing, the pressure, flow and RPM tests are no problem but I can't currently do the lift test ATM, that'd have to wait until April, which is the earliest I can get access to the same room and the time to do it. I can do those 3 tests, as well as the other testing for Petra this coming weekend.

Wow, that came sooner than I thought. Do you notice any more noise from the DDC 3.25 compared to the DDC 3.2, since it spins faster?

No, not really...there's a change in pitch similar to what's in the video link above, it's kind of subtle in the video but you can hear it. If anything, I think it may actually get a little quieter as the restriction goes up.

Good work WL!!

I knew that PM I recently sent would have some sort of negative recourse. I am done with PQ, just need to finish up this MCR-Stack and will do "average" loop flow rates.

Thanks skinnee



Looking forward to those results.

[JoeBar]

Thanks for your effort WL...!

[BringerOdeath]

Thx for doing the testing WL and looking forward to skinnees full on evaluation!! :P

[nysulli]

I wouldn't put too much stock into the PCB discoloration on DDC's. Both of those pumps look exactly the same when I took them apart prior to testing for a quick inspection. I would have done draw number if the one DMM I have didn't blow it's 10A fuse about 2½ years ago. I've been unable to find a replacement locally and I'm not about to buy another $100 DMM when everything else works on mine, I simply can't afford it. The analog I have only goes to 250m which is useless for these pumps.

thanks for the testing

as for your fuse, see if there's a grainger around you, I've had to replace a few fuses in DMM's and they've always had what I needed

http://www.grainger.com/Grainger/wwg/start.shtml

[zanzabar]

Sure thing, the pressure, flow and RPM tests are no problem but I can't currently do the lift test ATM, that'd have to wait until April, which is the earliest I can get access to the same room and the time to do it. I can do those 3 tests, as well as the other testing for Petra this coming weekend.

woot thats all i was interested in