Swiftech MCP35X and MCP35X Reservoir (Rev. 2)

When my venerable yet older MCP355 died, I was heartbroken. Well, as heartbroken as you can be about a water pump. As my first “real” pump it did its job for over two years. A job it may have done under duress. About a year ago, Swiftech stopped warrantying pumps that had their tops removed in favor of an aftermarket top. Mine had an XSPC reservoir top on it. Whether that is what did the pump in we’ll never know, but the fact that they no longer warranty pumps that had their tops removed at least introduces that potential.

As the MTBF for those pumps is 50,000 hours (or 5 years with 24/7 use), I shot Gabe (CEO of Swiftech) an email basically to test the waters and see if they could cover the MCP355 under warranty. I wasn’t fishing for an MCP35X and indeed specifically said I wasn’t asking for a review sample because  I have no proper testing equipment. Then I pleaded for a replacement MCP355. Even with their reputation for superb customer service, I didn’t expect much. Indeed, because it had been over two years and because taking the stock top off voids the warranty, Gabe’s hands were tied.

Then he offered to send a review sample of an MCP35X plus MCP35X reservoir.

The MCP35X Pump

Packaging and Contents

Just like the MCP350 and MCP355, the MCP 35X comes in a large-for-its-contents cardboard box. Unfortunately it wasn’t quite secure enough and didn’t make it to me in its cutout in the cardboard.

It was none the worse for wear though and operates just fine.

Within the accessory pouch is everything you need to add the pump to your loop. There are screws for two different mounting-medium thicknesses, two barbs with two plastic hose clamps, a foam sticky-pad and instructions.

The Pump Itself

Looking around the pump, this is not your average DDC. Its rated power draw (18W) is the same as the MCP355, but the top is anything but the same. It is a high-performance ‘aftermarket’ top straight from Swiftech. Martinm210, long an authority on all matters water, gives the machining of this top a rave review.

Why is it so nice that there is a high-performance pump top from the factory? Because it does not void your warranty! As mentioned before, a while ago Swiftech had to stop warrantying pumps that were used with aftermarket tops because the failures were quite possibly not the pump’s fault. Indeed, that practice continues with the MCP35X

That’s ok though, because there is already a great top installed on it. No need to worry about messing up your pump top install, potentially causing a leak and having it kill your pump, which warranty was voided by your attempt in the first place. That can be a costly mistake. Now you can just leave the already-strongly-performing top on and enjoy your full two year warranty.

There is one other huge benefit to this top – it is threaded for industry-standard G1/4 fittings, the reason (other than performance) people changed the top on the MCP350/355 to start with. Now, you’ll want to either use Swiftech’s barb on the inlet, or choose one with similarly short threads to keep it flush with the top; so keep that in mind when looking for fittings. The included 1/2″ barbs work just fine, so unless you plan on going with compression fittings you don’t even need to purchase extra barbs.

That’s not all that’s different about this pump. Water cooling gurus that enjoy decking out their builds and making them look extra clean will enjoy the fact that there aren’t awkward hold-downs sticking out of the pump any more. The holes for installation of the MCP35X are on the bottom, invisible after you install it. That requires a little more work on the user’s part but is well worth it for the clean look.

What’s the other reason many people get into water cooling? Silence! (shh) This pump is absolutely unique among all pumps available on the market today, as it can be PWM-controlled. If you didn’t notice the wiring coming out of the pump earlier, look a little closer.

The standard MOLEX-connected power and ground are there, as is the blue RPM wire we’ve come to expect on MCP350/355s, but there is an extra green wire that connects next to the RPM wire. That’s the PWM controller wire. No other pump on the market allows control like this one. You can use your BIOS or your motherboard manufacturer’s software to control your pump on the fly. Keep it absolutely silent for every day use and let it crank up when you need some extra cooling. Per Swiftech’s graph, the RPM maxes out at 70% PWM input and keeps it consistent through 100%.

Control from ~1,300RPM to ~4,400RPM is music to the ears of silent water cooling fans the world over. That said, once this pump is bled it’s very close to silent at full speed. I let my motherboard control it simply because it can and so the motor isn’t running all-out all the time, but the difference is minimal. It starts silent at low RPM and ends up at a level that qualifies in my opinion as really quiet.

If you don’t have PWM control on your motherboard or just want the pump to run full-bore, that’s fine too. Just don’t plug the connector in and presto, your pump runs full speed all the time.

The MCP35X Reservoir (Rev. 2)

The reservoir comes in a similar looking box and is well packaged, with bubble wrap protecting the reservoir from its heavy metal cap.

The parts for installation are inside a plastic bag within the reservoir. The reservoir and cap are encased in protective bubble wrap for safe transportation. Pulling them out of the container, everything is laid out nice and neatly.

As you see, it comes with everything you need for installation and use.

• The acrylic reservoir itself.
• One 1/2″ barb and plastic hose clamp (you only need one since the reservoir is attached directly to the pump’s intake).
• Two plugs for holes you don’t use.
• The hold-down nut (the one with a hole in the middle).
• Metal and sponge water filters.
• An o-ring for the seal between res and pump.
• A tiny metal dowel to anchor the reservoir’s direction.

The reservoir itself is very thick and well machined. All of the parts have a nice finish too. Swiftech definitely paid attention when designing this reservoir. The o-ring has a recessed slot for it to reside in on the reservoir’s bottom. There are six different holes for the dowell to rest in, so you can aim the reservoir’s inlet however you would like.

Speaking of inlet, there are three different options for you to use. Most reservoirs have one, maybe two possibilities, but this gives you the flexibility to do what you want with your loop. All in all, it looks like a great reservoir that will a) not void your warranty by requiring you remove the pump top and b) give you water right when the pump needs it, sitting right on top of the inlet. To top it off, once you install everything, it even looks quite nice.

Bleeding

There is one big but to this reservoir (there’s always one, isn’t there?). If you configure your loop for an inlet on the side of the reservoir, you may have a potential bleeding issue. Well, a lack of bleeding issue really (if you don’t know what bleeding is, check out the assembly and testing section of our Beginner’s Guide to Water Cooling). This pump is powerful. So powerful, in fact, that if you have a low restriction loop that lets it get to the upper end of its potential gallon-per-minute rating, the returning water seriously agitates the water in the reservoir. That agitation re-introduces bubbles into the loop and never allows it to bleed fully.

One solution is to use the PWM control on the pump to keep the pump’s speed down, after which it can bleed relatively well. Unfortunately, when the pump spins up to higher RPM (say, before your OS software takes control of the PWM), it will agitate the water and de-bleed the loop!

The loop I installed it on consisted of this reservoir and pump, a Swiftech MCR-320 radiator and an EK Supreme HF CPU block, with a little bit of tubing (not much) and that’s it. It constantly had bubbles going through the loop: not just little bubbles mind you, but audible bubbles like you’d expect when just starting to bleed your loop, which was annoying to say the least.

But it doesn’t have to be: Martinm210, one of the foremost authorities in water cooling, has come up with an elegant solution. The XSPC reservoir top for the MCP350/355’s had a tube down the middle that goes down to just above the pump inlet. It was one of the fastest-bleeding reservoirs you could get. Little did I know the tube was precisely why it bled so easily.

Martin came up with the brilliant thought of imitating the XSPC design manually. It’s so elegantly simple anyone can do it. Just take a spare barb and screw it into the threads opposite an inlet barb on the reservoir cap. Then put tubing on the spare barb down to about 1/2-3/4″ above the pump inlet. A picture is worth a thousand words though; here is his photo of the implementation.

After a bit of frustration with using the (top) side inlet with repeated de-bleeding (I like that; it should be added to the dictionary), I went with this method and it works like a charm. After starting up and dropping speed down to ~60%, the loop bled within minutes down to the stubborn little bubbles that take forever no matter what solution you go with.

One thing to note is that filling with this configuration is a little more tricky. You’ll have to hold the pump on its side after bumping it and fill via one of the side holes. It’s not too challenging, just remember to fill your loop before mounting the pump.

After the loop finished bleeding, I can turn the pump to full blast and won’t have to worry about de-bleeding again. Well done, Martin, well done!

Assembly & Finished Product

As this review is light on testing, the least we could do is show you how to assemble everything. Thanks to my HD camcorder, we’re able to do it in vivid detail.

Note – This is my first video how-to; please feel free to share your thoughts in the comments!

There you have it folks, an assembled pump/reservoir combo.

It’s a pretty good looking pair in my opinion, nothing to complain about the installation process or the completed look of the product.

Performance – Thank Goodness for Martinm210 and Skinnee

Unfortunately I don’t have any equipment for testing flow and pressure, but thankfully there are those that do. Those that have been doing the water cooling thing much, much longer than I have. Martinm210 is one of those people. He has kindly given permission to show how this pump performs using his graphs. You can check out his review of this pump & reservoir at his site, Martin’s Liquid Lab. While you’re there, be sure to check out all the other superb work Martin does!

That said, I’m not one to just yank a bunch of graphs from someone’s site. Martin generously gave permission to use everything we want, but you should really look at his site to get the full picture. What we will show you is how the MCP35X performs compared to its predecessor – the MCP355 with an XSPC (non-reservoir) top.

For all but the most restrictive loops – we’re talking loops that take you below 1GPM, which you don’t want to dip below anyway – the MCP35X out performs its older brother.

What’s interesting about this graph is the additional data set: pump RPM. It’s pretty evident why the MCP35X holds its head pressure as flow increases. It keeps the RPM up throughout the curve, all the way up to three gallons per minute; only then does it drop off.  The MCP355 with XSPC top drops constantly with flow increase, which drops its head pressure as the flow increases – a less than preferable situation.

Martin also tested the XSPC top on the MCP35X and “…it performed equally as well”, meaning that it’s the motor that makes the biggest difference. It’s a different animal too. If you got lucky and got the right PCB, some could change their MCP350 into an MCP355 with a little bit of solder and wire. That’s not the case here; you can’t turn an MCP355 into an MCP35X. If you want this performance, you’ve got to grab the new pump.

Some may think sustaining such high RPM might be bad for a motor. Indeed it increases power draw and potentially heat. However, that’s not much of a concern because as-is, you have a two year warranty; so let it hum along happily giving you great performance. You’re protected!

Definitely go to Martin’s site and look at the rest of his performance numbers. He compares the different pump configurations (pump alone, with MCP35X Reservioir (with the sponge and with the top-down tube mod) and with a separate reservoir ) and also does some power efficiency testing. In case you didn’t click it before, here’s the link to his review again. It’s well worth the read. Skinnee reviewed the combo as well and came to much the same conclusions, which you can read here.

Final Thoughts

There is no doubt about it; the Swiftech MCP35X and MCP35X Reservoir (Rev. 2) is a superb combination for anyone looking for excellent performance out of a pump and reservoir.

I’ve always liked res-on-pump combinations. Not only is the water right there at the pump at all times, assuming proper installation, it takes away two potential leak points for tubing/barbs that would join a separate reservoir with the pump. The only drawback is for those that run low restriction loops. In my test loop, above about 50-55% on the PWM control it would de-bleed itself and introduce bubbles back into the loop. Martin came up with a brilliant solution that works great. The only thing that would make the combo better is if Swiftech could come up with a built-in solution like that.

Except for that one qualm, there is absolutely nothing to complain about here. The pump is quiet, the reservoir does its job with plenty of configuration options and they do it with better performance numbers than an MCP355 with a solid aftermarket top. It also does all of that with a two year warranty backing it up. This combo definitely deserves to be Overclockers Approved.

– Jeremy Vaughan (hokiealumnus)