Swiftech MCP35X2 Pump

Posted: January 29, 2012 in Pumps
Tags: , , , ,


While I am not going to go into detailed testing here specific to the 35X2, I will discuss my subjective thoughts and include the previous work on the 35X pump that can be used to consider noise. They are after all the same exact pump motor and very similar in pump top style, the only difference is we have two pumps that can produce basically twice the pressure as the same RPM.  First let’s take a look at the 35X results from my pump noise testing round 1.

If the 35x (Single Pump) is decoupled from direct metal contact, it holds a noise level very nice and low a majority of the operating RPM range up to about 2.3GPM in that previous test.  It isn’t until you push those peak RPM levels when noise starts to pick up and a more noticeable whine develops.  This is where running two pumps does have a slight noise advantage over a single pump.  It essentially produces the same amount of pressure at half the RPM level so you can operate at lower RPMs and still have gobs of power.  Subjectively I would rather operate the 35X2 at 40-50%%PWM over a single 35X at 100%.  The lower RPM is superior in both noise and heat.

Then there is the “HOW YOU USE IT” question.  If you take advantage of PWM and throttle the pump speed according to temperature needs, you can get the best of both worlds of low noise and monster pumping power performance when you need it.  In my long-term 35X use I found this to work extremely well.  When surfing the net and doing office related tasks, I had speedfan dialing the pump down to 30% or so levels which is how it operates most of the time in complete silence.  Then when gaming, I typically use headphones or when bench-marking I don’t mind a little extra noise, that is the only time the pump cranked up the power automatically to gain maximum performance at the expense of some noise.  When wearing headphones I can’t hear the increased pump speed regardless, so it was an excellent and smart way to run the pump.

Pump Heat

Pump heat of the DDC series pumps can be high producing a base that is hot to the touch and should be considered as part of the install depending on how the pump is used.  If you utilize PWM to throttle the pump down in speed a majority of the time, the heat levels will likely be kept down to levels you can ignore.  Pump heat is also significantly dependent on the restriction level of the system where the more restrictive (lower flow rate) the less heat.  You can read about some of the DDC pump heat testing I’ve done here.

In addition an active or passive heatsink can also be an effective way to help not only keep the pump cooler, but also reduce the amount of heat added to the water/coolant.   At the moment, the MCP35x-HS would not fit without modifying it, but  a 35X2-HS (heatsink specific to this pump) is in the works and should be available toward the end of February or early March.

At a minimum I would suggest using only two of the neoprene pads on the outer edges such that you have about a 1/4″ of air space under the pump centers and place the pump in a location where air can blow under the two pumps.

Alternatively, another effective way to both decouple and cool the pumps is to allow the pump to be suspended by tubing. The best mount in terms of noise and heat is no mount at all..:)

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  1. Tingez says:

    You just made my mind up on what pump/s system to get for my own personal rig. As well as the pumps i will be recommending in my shop. I love this pump setup. Swiftech have done a really good job with this product and for that matter the single unit system too.

  2. Elke says:

    e, jednakowoż teraz
    przyjechało mocne pociągnięcie. Elke Zamknięcie sznurka
    wyskoczył w dłoni, zniknął w zaroślach. Huk tratowanych
    flor roslinnych,
    skończony potężnym beknięciem. Wcześniej po wszystkim.

  3. Gadgety says:

    Hey Martin. I’m putting together my first water cooled computer and since the basement ambience is 5-15 degrees celsius cooler (depending on time of year), I’m planning to put a remote radiator there. The extra length of tubing will be about 8-10 feet round trip.This dual pump will come in handy with its extra head. The temp advantage, and noise isolation makes it appropriate to have the pump by the radiator and keep all noise out of my home office. I haven’t got everything figured out yet, for example – I’d like to keep the reservoir at the highest point to enable air bubbles to exit there, rather than by the pump/radator. I still don’t know how to handle cabling, and placing the pump remotely will complicate the PWM controlling off the motherboard+the 12V power supply. I’m not totally clear as to what it will mean in terms of maintenance either (i.e. opening loops, running up and down the stairs etc). Any suggestions, or warnings are welcome.

    • Martinm210 says:

      I have seen it done before. My only suggestion is to use larger ID tubing as the length does start adding some restriction. A nice large reservoir would make filling easier too. I would probably place it right before the pump. It’s a good setup that way. Been done before.

  4. Michael says:

    Question: Would you recommend two swiftechs 35x with a single top connected with a tube to avoid vibrations or would you recommend a dual top like for example the EK-DDC Dual TOP V.2 G1/4 – Black Acetal?

    • Martinm210 says:

      I think either option works fine. Dual top is just more compact and cleaner looking.

      • Michael says:

        I have another question: is there any advantage of using a different pump top for Swiftech Extreme Flow Dual 12v DC Pump like the EK Water Blocks EK-DDC Dual TOP V.2 G1/4 instead of the original dual pump top of swiftech or is it just for aesthetics?

        • Martinm210 says:

          Mostly aesthetics, it’s a pretty optimized top already. I found the 35x top and xspc tops to be pretty close depending on the barb used so I assume the same is true for the dual top.

  5. Louis says:

    Hello Martin,
    I am studying engineering and am working on an independent project which requires and adjustable flow rate pump. I purchased one of these as a possible option. I was wondering whether you know if there is a minimum frequency at which they will accept pwm input?

    Also I have run into an issue which could be a known issue or could be one of those dud pump issues. I have noticed that even with pwm turned off, my pump tends to have a high flow rate initial spurt and then drop down to an extremely low flowrate. Is there anything you can think of which would account for this, or did I get a dud?


  6. Anthony says:

    MOBO: Asus p9x79 Pro
    CPU: i7 3820
    RAM: 8gb G-Skill Rip jaws Z 2133
    video: 2 x HIS Radeon HD 7970(Crossfire)
    SSD: 2 x Samsung 840 Pro SSD (Raid 0)

    Water cooling parts
    2 x Coolgate quad 120mm Radiator
    XSPC RayStorm
    2 x Swiftech Komodo 7970 full cover. (in series)
    Alphacool vp655 vario pump(d5)
    EK x-top for pump
    primochill 1/2in rigid tubing

    My idle CPU is stead 34c while the GPUs idles at 41c. The GPUs spike to mid to high 60c, have seen them close to 70c when playing games and they cards are not at full load.. My ambient temps are normally around 25c – 26c. The idles are a bit high but I think that its due to the higher ambient. But the load temps seem to be too high. Could this just be a flow issue? Is a single D5 not enough to pump this loop?

    I am thinking it is the pump setup and was thinking about using the MCP35x2. What do you think of this?

    • Gadgety says:

      I’m looking into the MCP35x2 as well, but I’m concerned what happens if one of the pumps inside the housing breaks. Do I have to get an entire 35×2 unit then? In that case, better to go with dual MCP35x pumps in separate housings instead.

      • Anthony says:

        Well you would run dual pumps for added pressure. This pump is just 2 mcp35x’s. So if one breaks down the other will continue and keep the loop flowing. That means you would have to buy and install a new mcp35x2. Since the unit is sold as one, the warranty would be void if you take one pump of four replacement.

    • Louis says:

      I am not an expert on computer cooling loops, but looking at specs for pump, the mcp35x2 does not have a higher flow rate so much as a higher pump pressure. So if you are noticing that the maximum flow rate you are getting through the system is very low, then you probably are loosing a lot of the pumps energy to drag and pressure drops and a higher pressure pump system will do the trick. If you are noticing that you get pumps full flow rate in the system, but system is still running hot, then you probably will need to add more radiators or more fluid.

  7. JackNaylorPE says:

    Anyone know the dimensions of this thing mounted on the pump specific 35X2-HS heat sink. All the US sales sites, swiftech site, nada.

  8. Judelexan says:

    Thanks for this great review; I’ve actually been eyeing this pump for a new build. Reading your site for a few weeks has increased my knowledge immeasurably, and prevented me from making some very costly mistakes.

    Now, on to making some *different* costly mistakes :)

  9. JackNaylorPE says:

    Question if I may Martin….. I took the lower HD cage outta the Phanteks Enthoo and have the 35×2 there (under the top 3) which gives me a height restriction….. been arguing with myself between the following choices ….. 90 elbow into “optimal inlet or 45 elbow to “alternate” inlet ?

    • Martinm210 says:

      90 into optimal would probably have a very slight edge since an external elbow is fairly large in ID and the distance is pretty far away, The alternate inlets are generally a pretty small ID within close proximity of the impeller causing the flow into the impeller to be less uniform. That’s a powerful pump with plenty of head to spare though so either would work just fine.

      • JackNaylorPE says:

        That was what i was going to do if I didn’t her from ya before firing it up :)

        I’m getting a bit concerned about the powerful part a start up day nears :) …. my 1st rigid acrylic build and the “pushing in” was easier than I expected. I did use short (2.5″ on outlet / 3.5″ on inlet from res) flex tube compression connections on inlet and outlet of pump in an attempt to minimize vibrations……

        Wish there was a way to tone it down on start up….. planning to run at 40-50% PWM but gotta start it up and get into BIOS first :) …. hmmmm…. see any harm in filling loop and testing with just one pump powered ?…. setting the BIOS to 50% max and then shut down, rinse and repeat ?

  10. JackNaylorPE says:

    Well just wanted to let ya know all up and running …. have 4.6 Ghz at 1.38 VID and temps all under 75C …. only issue is can’t get M6F to tone down the speed …. lowest I have seen is 2800ish but mostky above 3050 rpm at idle (CPU temp = 26C). FanXpert2 “says” I’m at 38% PWM but rpm of 3040 is more like 68% .

    • Judelexan says:

      While I haven’t used the Asus software, I had a similar problem with the Gigabyte software on my board. Just set it to the lowest you can (so you don’t end up rocketing too much air into your loop at startup and have SpeedFan take over at log in.

      • JackNaylorPE says:

        Well got it “Golden” now ….. instead of trying to “control” how FanXpert2 does it, I let FanXpert2 do it’s thing and ran the tuning protocol….. worked like a charm ….. I’m now running a custom profile that gives me:

        13% PWM @ 0C
        13% PWM @ 20C
        20% PWM @ 50C
        75% PWM @ 70C
        100% PWM @ > 70C

        CHA fans (rads) are running at :

        0% PWM @ 0C (off)
        0% PWM @ 20C (off)
        32% PWM @ 45C
        92% PWM @ 72C
        100% PWM @ > 72C

        Weird things is …. in FanXpert’s test, it\ recorded the following pump speeds.

        0% PWM = 1230 rpm
        10% = 1243
        20% = 2477
        30% = 3824
        40% = 4485
        50% = 4470
        60% = 4485
        70% = 4440
        80% = 4470
        90% = 4485
        100% = 4488

        • Judelexan says:

          My results with SpeedFan are identical… odd that there is such a tight range

          • JackNaylorPE says:

            SpeedFan won’t work with the Maximus VI Formula :(

            I don’t think it’s accurate as in practice I see a much wider range of rpms as reported by AiSuite 3

            I have reprogrammed it tho ….

            13% PWM @ 30C
            25% PWM @ 35C
            40% PWM @ 40C

            That pretty much caps me at 30% PWM at 50C and keeps pump speeds in nice quite range as GPU goes from 40-45C