MCP-655 or 355?

Well, I figured this has surely been discussed somewhere in depth, but my searchfu must be weak, because when I searched "355" here I didn't find too much.

I'm looking to build a second water-cooled computer, and I'm not sure which of these two pumps would be best suited. I currently run an MCP-655 in my main computer, and it seems to do well. It's currently running the following loop: MCP-655 -> Storm -> Low-Profile Maze4 -> PA120.3 -> Res. The pump is located above the radiator and below the res, for what it's worth. I'm running Masterkleer 7/16" tubing and everything has 1/2" barbs stock.

Before that it was running the same loop, but with two low-profile Maze4's. I still had the IHS on my Opty at the time, so I really can't say how much only running one card has helped the temps in the loop since I removed the IHS at the same time I got rid of SLI.

Now, if I hadn't come back here to read up a little more, I probably would've just snagged another 655, but the 355's smaller form factor and the "Water Cooling Round-Up" thread got my attention. In that thread, it mentions the 655 as having better free flow, but maybe being better for single block systems. It says the 355 has low free flow (which can be improved with aftermarket tops, but will that get it up to the 655's flow abilities?), but better pressure, along with a blurb about it being good for multi-block systems.

With my current system, do you think the MCP-355 would perform better than my current MCP-655? I doubt it would be worth upgrading over, but since I'm looking to build a second WC'd rig for the wife, I figured I could either buy her all new stuff and keep mine, or buy me new stuff and move over the other stuff I'm not using to hers.

When I build the second rig, I'll be using a PA120 (not sure if I'll use the 120.2 or 120.3 yet), a Swiftech Micro Res, my leftover low profile Maze4 for the GPU, and an Apogee GT. The fans on all my rads are 120mm Coolermaster Silent LED fans in a push-pull config.

Should I get another 655, or will the 355 do better in these two-block loops? Or is it really a toss up by a degree or two either way and you'd just go for whichever was cheapest at the time?

I bought the 655 for my system. I'm using it with a fairly restrictive Swiftech Storm rev2 CPU block and a Maze 4 GPU block (non restrictive type of block) and the sucker SHOOTS water into the reservoir like a fountain with vigorous force.

I'm using an Alphacool Coolplex 10 reservoir and originally had problems with it because of the strength of my pump. It is kind of hard to explain but inside the rez, there is a tube that extends about half way into the reservoir itself. This is supposed to be the in tube that helps facilitate bleeding out the bubbles by keeping them from entering the out tube and back through the loop again. The problem is water was shooting out into the top of the reservoir through the surface of the water that already filled it, causing tons of turbulance and more bubbles. I finally removed the inner tube forceably so that the incoming water has to push against more water inside the rez and can't force its way into the top of the rez and create a splashing/bubble effect. There is still a vigorous vortex effect constantly going on in the rez.


If I didn't have the storm I think I might have problems with air bubbles in my system. In short, the 655 will work fine. The 18w DDC is supposed to be the best for pressure and really good on flow with a modded top, but I'm doubting it's worth it for me personally to upgrade since the 655 already works so well.

It really wont matter as far temps go so I would say pick up the MCP-655 it is $65 compared to a MCP-355 and new top which is $100.

I kinda figured that would be the case, but I always like to run it by the judges here first. My current 655 puts out a good bit of turbulance into the res, and it's a double-5 1/4" bay res at the very end of the loop. Not so much turbulance that bubbles are an issue or anything, but enough that the res has a nice waving line at the water's top. =)

Does the MCP-655 retail for $65 anywhere, or are you just going off the average price you can pick one up used? (I noticed most of the ones in the classifieds here go for $65 shipped, it seems)

the MPC655 is $69 at sidewinder computer

http://www.sidewindercomputers.com/swmc12vdcpu.html

The both have roughly the same specs...

but i think the is much 355 smaller, good to go for lian li PC V 1000s

Lian Li's ... ick. These systems are in Mountain Mod's cases. I'm pretty sure there's enough room for me to crawl inside my case and live comfortably for a week if my wife ever puts me in the doghouse. lol

Are you talking about a case like this:



I have both a lian li and a MM. They are very differnt cases both with good and bad points.

I honestly think the Lian Li is a much better quality case in respect to design and materials considering they are priced fairy equally.

Look at MM it doesent even have a USB slot at the front! (ANY cheap 40 dollar china made CRAP BOX has USB ports at the front).

It doesnt even come with spare screws, CD rom covers, or parts such as fans you have to buy them seperatly!

You have to unscrew 24 screws just to open your case compared to the neat Lian Li design.

Taking out a HD from a MM U2 UFO is a friggin pain you have to take out the fan + the brackets then unscrew the HD from the brackets. Lian Li just use a HD cage with clips and wheels, no tools needed!

The MM "evolution continues" but its like a prehistoric animal compared to the already refined and elegant Lian Li.

It's all in taste and personal preference ... to me, the Lian Li is a ridiculously overpriced box that's about as plain looking as they come. I wouldn't pay half Lian Li's asking price, and the fact that they include USB headers on the front of their cases just like the cheap-o $40 chinese boxes do doesn't impress me - I'd prefer not to have a built-in front panel so that I can my own equipment and put it where I want it. Just about every multi-function/card reader 5-1/4" front panel device out there comes with USB ports and sound jacks now, so that's really not an issue for me.

I don't mind taking the 10 seconds required to undo screws, I have dozens of spare thumbscrews lying around, and I have to install or remove a hard drive maybe once a year, so that's not really much of a hindrance, either.

The Opti-1203 is spacious, it's easy to assemble and route your system in, and most importantly to me, it doesn't look like a plain box.

So to summize ... thanks for all the suggestions. Looks like pump size is the only real issue between the two pumps, and I've got plenty of space, so we'll just go with another Laing D5.

Thanks.

I've tried the D5 (mcp655), DDC(mcp350), and DDC-2(mcp355). I personally won't go back to a D5 over a DDC-2. The DDC-2 is considerably smaller and quieter than the D5. If you want uber quiet, the DDC is one of the quietest pumps you can get.

I'll admit the DDC+ is very, very quiet - even with a Petra's top. The thing is, most loops don't need that much horsepower to run well. My MCP655s (D5) does very well on the P3 setting and is very quiet when turned down that far - my HDDs spinning up make more noise.


IMO - Stick with the MCP655. One MCP655 on P3.2 runs my loop (see sig) with no problem ...

Yeah both are good PC casese and it is down to personal preference.

Can the MCP350 go though a tripple rad, storm, and a GPU?

And is it quieter than say a Raptor HD?

Mycobacteria said:

Yeah both are good PC casese and it is down to personal preference.

Can the MCP350 go though a tripple rad, storm, and a GPU?

And is it quieter than say a Raptor HD?

Click to expand...

Yes, and still have pressure to spare. The MCP350 is an incredible pump. It's just more expensive.

Are you asking about the MCP350 (8W) or the MCP355 (18W)?



The MCP355 isn't as powerful as the MCP655/D5 but it's quieter and uses 3/8" barbs. It's about the same price.
With a Petra's top it's near the same power as the MCP655 but quieter and more expensive.
The 8W MCP350 may not be enough for your loop.

I'm pretty sure an MCP655 or an MCP355 w/top would be plenty - w/out the top may be pushing it depending on your rad ...

QuietIce said:

Are you asking about the MCP350 (8W) or the MCP355 (18W)?



The MCP355 isn't as powerful as the MCP655/D5 but it's quieter and uses 3/8" barbs. It's about the same price.
With a Petra's top it's near the same power as the MCP655 but quieter and more expensive.
The 8W MCP350 may not be enough for your loop.

I'm pretty sure an MCP655 or an MCP355 w/top would be plenty - w/out the top may be pushing it depending on your rad ...

Click to expand...

I always thought the 8w was still extremely powerful. Probably for it's size.

But yeah, the 18w (DDC+/DDC-2/MCP355) is definitely plenty for that loop with the 1/2" mod or an aftermarket top. The 1/2" mod is basically changing the top 3/8" barb at the right angle to a 1/2" top that feeds right into the center of the pump. It requires a 1/2" drill bit or something similar, a barb, and some sort of epoxy to hold the barb in place without leaks. I have done it to my DDC-2, it's quite easy, sadly it voids warranty.

sorry for moving away from the topic but after reading your posts I'm feeling abit worried about my pump.. I'm using a 655 n u guys report that water gushes out. at first my pump did exactly what u guys were saying. but after adding more water in my loop so that my res is almost full I don't get that whirpool effect anymore. its more or less a little movement in the res. n I got to be feeling even more worried because my loop aint restrictive at all. a bix2 n apogee. and I've been running the loop for a few days already so it should be fully bleeded.

btw whenever I start my pump I can hear abit of air in the pump. but after a few secs its alright. is this normal?

Sounds like you have some air stuck in your pump. Turn on the loop and rotate the pump/case around and see if you get any bubbles.

QuietIce said:

Are you asking about the MCP350 (8W) or the MCP355 (18W)?



The MCP355 isn't as powerful as the MCP655/D5 but it's quieter and uses 3/8" barbs. It's about the same price.
With a Petra's top it's near the same power as the MCP655 but quieter and more expensive.
The 8W MCP350 may not be enough for your loop.

I'm pretty sure an MCP655 or an MCP355 w/top would be plenty - w/out the top may be pushing it depending on your rad ...

Click to expand...

A bit of clarification here. The MCP355 has twice the head pressure rating of the MCP655 (20ft vs 10ft), which means that it can push more flow through higher restriction. The 655 however has a higher flow rating (317gph vs 120gph for the 355). In real world comparisons, they will be about on par on flow given higher restriction. With an aftermarket top, the 355 outperforms the 655 both in pressure and in resultant flow as the top (or inlet mod as mentioned above) increases its flow by about 75%.

An MCP350 has about 20gph lower flow than the 355, and the head pressure is only 13ft vs. 20ft for the 355. So, unless you are running a Storm, you should be able to run a 350 with a triple rad and blocks like the Apogee Gt or Fuzion and get excellent performance. Flow only helps up to a certain point anyway as far as measurable results go.

I personally opted for a 355 with top as that is the best performance combination and yet is very quiet. However, I'll bet with my setup that I would hardly see a performance difference switching to a 350. And if you really want the quietest pump, then the 350 is the way to go. I think that it makes sense to use either the inlet mod or an aftermarket top particularly with the 350 as the increase in flow is about 75% for the DDC pumps, and that increase with this pump probably is enough to see the difference over just using the stock top.

Petra's said:

DDCT-01 Specifications (w/18W DDC-2):
Max. Head Pressure (at 12V): 8.1 psig (18.68 feet - 5.7m)
Max. Discharge (at 12V): 3.5 GPM (210 GPH - 13.25 LPM/795 LPH)

Stock DDC-2 (18W) Specifications:
Maximum Head: 20.2 ft (6.1 m)
Maximum Discharge: ~ 120 GPH (454 LPH)

Laing D5/Swiftech MCP655 Inline 12vDC Pump Specifications:
Maximum Head: 11 ft. (3.35 m)
Maximum Discharge: ~ 317 GPH (1200 LPH)

Click to expand...

Even with the top the MCP355 does not out-perform the MCP655 in flow rates. If you look at the Swiftech flow/pressure graphs (admittedly doesn't include the top) you will see the pressure is higher with the MCP355 only up to ~1.25 GPM. Once it's past that it has less pressure than the MCP655. Since the top actually lowers pressure from the stock MCP355 (though the flow is higher) I suspect the break-even flow rate/pressure for it isn't much higher. Eh, there's probably not enough difference between any of them to see a better OC.

Man, you've aroused my doubts enough I'm going to have to get an MCP655 to test along with the other pumps - and I'll need two pair of 1/2"-3/8" reducers ...

Well, after getting my case all back together, I've decided to run water-cooling in the wife's, too. So I turned it off the other day (it is almost always running), and MAN, I had forgotten how noisy her computer is. The room got eerily quiet.

But now with her computer off, I can finally notice the noise of my D5. lol. Go figure. I already picked her up a used D5 now, too, but with all things being pretty comparable aside from noise, I may just have to switch them out for a couple of DDC+ now.