How much pump is enough? How much is too much?

[Cathar]

This is a copy of a couple of posts from the original thread that I started at OCAU. For those who wish to criticise, I do appreciate that there are limitations and things not accounted for, and I am in the process to greatly expanding the scope of these posts into an article, for which I will invite peer review on in the next few weeks and hope to get it published on a web-site somewhere (here at Procooling?).

In any event, here's the post:

__________________________________________________ _____________

HOW MUCH PUMP IS ENOUGH? HOW MUCH PUMP IS TOO MUCH?


Introduction


I just wanted to investigate the phenomena of chasing ever larger pumps, and bring in some figures to explore just when "too much pump is bad".

First let's start with our challengers, all configured for in-line operation.

Eheim 1046, adds around 1.5W of heat to the loop
Eheim 1048, adds 3W of heat
Eheim 1250, adds 9W of heat
MCP600, adds 8W of heat
MCP650, adds 15W of heat
Iwaki MD-15R @ 60Hz, adds 22W of heat
Iwaki MD-20RZ @ 60Hz, adds 31W of heat
Iwaki MD-30RZ @ 50Hz, adds 50W of heat

Let's assume that we're watercooling an exceptionally hot CPU, that's putting 100W of heat into the water cooling loop under load.

Let's assume that we're using a Cascade waterblock, and for our CPU die it has a C/W curve relation that's roughly shaped like this:



Our theoretical loop consists of the Cascade block, 2 meters of 1/2" ID tubing, 1/2" barbs, and a Thermochill 120.2 radiator.

Against each of the above pumps, we arrive at the following flow charts:



For our radiator performance curve, we'll use the following graph, and use the pink line on the graph as befits two moderately powerful (35dBA) fans, being good performance while being fairly loud, but not insanely so.



Okay, so that's all the information we basically need to make our predictions.


Results


For each of the pumps we see that we'll get the following flow rates, and also the corresponding radiator C/W, and waterblock C/W at that flow rate:

Eheim 1046, 3.2 LPM, 0.045, 0.187
Eheim 1048, 4.2 LPM, 0.044, 0.178
Eheim 1250, 5.2 LPM, 0.043, 0.172
MCP600, 5.7 LPM, 0.042, 0.169
MCP650, 5.8 LPM, 0.042, 0.168
MD-15R, 6.7 LPM, 0.041, 0.165
MD-20RZ, 8.7 LPM, 0.040, 0.159
MD-30RZ, 10.0 LPM, 0.039, 0.157

Okay, so the CPU heats up by the CPU wattage dissipated by the waterblock's C/W at that flow rate. The water temperature rises above ambient by the radiator's C/W at whatever flow rate multiplied by the CPU wattage plus the pump heat wattage being added to the water.

This now gives us a predicted correlation for the relationship between the final CPU temperature as affected by the flow rate, but more importantly also after factoring in the pump heat.

Eheim 1046, WB delta = 100W * 0.187C/W = 18.7C, Water delta = (100 + 1.5)W * 0.045C/W = 4.6C, Total CPU temperature = 23.3C above ambient
Eheim 1048, WB delta = 17.8C, Water delta = 103 * 0.044 = 4.5C, Total CPU Temp = 22.3C above ambient
Eheim 1250, WB delta = 17.2C, Water delta = 109 * 0.043 = 4.7C, Total CPU Temp = 21.9C above ambient
MCP600, WB delta = 16.9C, Water delta = 108 * 0.042 = 4.5C, Total CPU Temp = 21.4C above ambient
MCP650, WB delta = 16.8C, Water delta = 115 * 0.042 = 4.8C, Total CPU Temp = 21.6C above ambient
MD-15R, WB delta = 16.5C, Water delta = 122 * 0.041 = 5.0C, Total CPU Temp = 21.5C above ambient
MD-20RZ, WB delta = 15.9C, Water delta = 131 * 0.040 = 5.2C, Total CPU Temp = 21.1C above ambient
MD-30RZ, WB delta = 15.7C, Water delta = 150 * 0.039 = 5.9C, Total CPU Temp = 21.6C above ambient


Discussion


Overall I think the patterns established speak for themselves. All of the high-flow focused pumps lose out significantly due to the wasted strength of their motors in comparison to the flow rates that can be realistically pushed. The high-head, low-moderate flow pumps (MCP600, MD-20RZ) perform the best as the ratio of motor heat to the final corresponding flow rate means that they are operating more efficiently for our proposed water-cooling scenario.

If we doubled the radiator effectiveness, which could only be achieved through exceedingly noisy fans, or using two such radiators (and a corresponding amount of fan noise), we get to the situation where the MCP600, 650, and the MD-15R all pretty much still fall on each other, the MD-20RZ pulls a slightly more significant lead, but the MD-30RZ still fails to catch the MD-20RZ while consuming a boat load of power in the process.

Of interest is the relative closeness of the Eheim 1048 and the Eheim 1250. If instead we chose a single 120mm radiator the difference between the two drops to 0.2C, or next to nothing, and so the Eheim 1048 would have to get the choice every time out of the Eheims, but the MCP600 still would be the first preference if its small amount of extra noise is not an issue. All of the other pumps become rather unattractive in a single 120mm radiator scenario where even the MD-20RZ should be avoided.

The Eheim 1046 is totally behind the knee of the curve in all respects.

So to answer: How much pump is enough, and how much pump is too much? I can make the following general recommendations:

Single 120mm radiator: First choice: Swiftech MCP600 or AquaXtreme 50Z. Silence Choice: Eheim 1048
Dual 120mm radiator: First choice: Iwaki MD-20RZ, Second choice MCP600. Silence Choice: Eheim 1048 or 1250
Larger radiators: Iwaki MD-20RZ all the way, with the MCP600 as a good second option.

I think it could be safe to say that if you didn't know what pump you need, and don't have the dollars to spring for the Iwaki MD-20RZ, then the Swiftech MCP600 (aka AquaXtreme 50Z) would have to be the single safest bet. For the performance freaks, the Iwaki MD-20RZ can't be overlooked. Avoid anything stronger than the 20-RZ though - it is a total waste - your CPU will be hotter - your water will be hotter - and you'll be sucking down more electricity while being worse off - there's no good news here at all. The Eheim 1048 puts in an admirable show, with the Eheim 1250 perhaps giving the best performance for low noise, and the Eheim 1046 should simply be avoided unless you have a specific need for it (low space and low noise).

The Iwaki MD-15R holds a bit of a no-mans-land position, being large, powerful and hot, but not really offering anything much to show for its go. Both the MCP650 and MCP600 are better, cooler, and less power hungry choices. The MCP650 fits the bill adequately as a very close runner up to the MCP600 in all scenarios, and is a worthy successor to the MCP600 once expected pump life-span is taken into the equation.


Summary & Conclusion


Recommended pumps:

Performance: Iwaki MD-20RZ
Jack-of-all-trades: Swiftech MCP600/AquaXtreme 50Z
Silence focused: Eheim 1048

Broad guidelines on pump selection:

• DO NOT select a pump that draws more than 50W of power. Performance will not improve further and the pump will be drawing more power than is needed, effectively being a waste of electricity which just shows up on your power bill. Pumps drawing much more power than 50W will actually make your CPU hotter.
• In general avoid pumps that put more than 16W of heat into the water per 120x120mm of radiator area (or equivalent). Match your pump to your available radiator capacity so that pump heat is not a major player in your water's temperature. In general, try to keep pump heat to radiator capacity down below 12W of pump heat per 120x120mm of radiator area.
• Try to choose a separated armature pump (spinning magnet around the impeller) as opposed to a canned motor (eg. Laing style), or electro-magnet motor (eg. Eheim style) as the separated armature design minimises motor heat transferral into the water
• Avoid pumps with less than 1.0mH2O of pumping pressure at 3.5LPM flow rate (or 3' of pressure @ 1gpm), unless you have a very specific need for some particular pump (space requirements). Such pumps are too weak and performance will suffer noticably.
• Try to avoid "high flow" pumps (pumps with >20LPM peak flow rates). Such pumps tend to have the wrong impeller design and flow characteristics for water-cooling use.
• Choose pumps with at least 6LPM of peak flow rate
• Choose pumps with at least 1.5mH2O (5') of peak pressure
• When trying to decide between two pumps where one pump has more peak flow than another pump, then so long as the rated peak flow rates are at or above 10LPM, always choose the pump that has the higher peak pressure rating, over the pump that has the higher peak flow rating. If the peak pressures are about equal, but both offer peak flow rates above 10LPM, choose the pump with the lower peak flow rate as it will add less heat to your system.

[Cathar]

Plotted a graph and worked out some figures for some in-series pump solutions in order to explore the "ideal" pumping scenarios I touched on above.

2 x Eheim 1048 => 6W of in-line heat
Swiftech MCP600 @ 13.8v => 11W of in-line heat
Iwaki MD-20RZ @ 50Hz => 25W of in-line heat
2 x Swiftech MCP600 @ 12v => 17W of in-line heat
2 x Swiftech MCP600 @ 13.8v => 23W of in-line heat

The PQ curves work out as follows:



Flow, radiator C/W, and block C/W works out as follows:

2 x Eheim 1048, 5.6 LPM, 0.042, 0.169
Swiftech MCP600 @ 13.8v, 6.8LPM, 0.041, 0.164
Iwaki MD-20RZ @ 50Hz, 7.5 LPM, 0.040, 0.162
2 x Swiftech MCP600 @ 12v, 7.2 LPM, 0.041, 0.163
2 x Swiftech MCP600 @ 13.8v, 8.7 LPM, 0.040, 0.159

...and our predicted CPU temps are:

2 x Eheim 1048, WB Delta = 16.9C, Water Delta = 106 * 0.042 = 4.5C, CPU Temp = 21.4C above ambient
Swiftech MCP600@13.8v, WB Delta = 16.4C, Water Delta = 111 * 0.041 = 4.5C, CPU Temp = 20.9C above ambient
Iwaki MD-20RZ @ 50Hz, WB Delta = 16.2C, Water Delta = 125 * 0.040 = 5.0C, CPU Temp = 21.2C above ambient
2 x Swiftech MCP600 @ 12v, WB Delta = 16.3C, Water Delta = 117 * 0.041 = 4.8C, CPU Temp = 21.1C above ambient
2 x Swiftech MCP600 @ 13.8v, WB Delta = 15.9C, Water Delta = 123 * 0.040 = 4.9C, CPU Temp = 20.8C above ambient


Summary

As expected, the 2 x Eheim 1048's pretty much exactly match a single Swiftech MCP600, and provides the best all-round solution when silence is required.

The single MCP600@13.8v shines through out of the blue here as the most promising single pump solution. It is only bested by the dual 13.8v MCP600 solution, and even then it's only just. The MCP600 pump would require a single 2A rated 13.8v PSU to give this sort of performance. Jaycar sells a suitable Switch-mode wall unit here for $60. They also offer a cheaper, somewhat border-line solution here for $30.

The 50Hz Iwaki MD-20RZ comes extremely close to matching the 60Hz Iwaki MD-20RZ as the best all-round single pump solution.

The 2 x MCP600's @ 12.0v, as described above, provide an excellent alternative to the Iwaki MD-20RZ solutions.

The 2 x MCP600's @ 13.8v pretty much exactly model the "perfect pump" scenario that I was describing a few posts back, and offers a significant gain over even the 60Hz Iwaki MD-20RZ. Now 2 such pumps would be drawing around 33W of power, or about 2.4A @ 13.8v. You would probably want to use at least a 4A rated 13.8v PSU to power the pumps up from standstill.

I still hold great confidence in saying that the "ideal" water-cooling pump, that is a realistic and feasibly built possibility (based on the MCP600), would be:

6-8mH2O (20-26') of peak pressure head
12-13LPM (3.2-3.4 US GPM) peak flow rate
25-30W nominal power draw (when in operation)
12VDC
Separated Magnetic Armature design (~16-20W of heat added to the water)
Centrifugal pump

Any pump which has specs stronger than this starts to take strides backwards in terms of offering better performance.

[murray13]

GREAT article!

Only drawback is that it makes an assumption that you are only going to water cool the processor. Personally I would like to see the numbers for a full system being cooled. Example: CPU, NB, GPU, and maybe even a HD in the loop as well. The only other thing I would have liked to see is the numbers for the 30RZ at 60Hz. It would put things into a little better perspective for those of us here in North America. It still only adds about 50W of heat but has a little better numbers.

Just my two cents.
Thanks for bringing it over here Stew, not all of us get to OCAU all the time.
Dave

[Ruiner]

Nice article. I think I'll be swapping my muffled D4 out for my old 1048. The whine is getting to me.

Re: the post above,
I thought of that for my rig, but the swiftech gpu block is pretty low restriction. I've never read of a good reason to wc a NB, let alone a HDD.

[Cathar]

Originally Posted by murray13

GREAT article!

Only drawback is that it makes an assumption that you are only going to water cool the processor. Personally I would like to see the numbers for a full system being cooled. Example: CPU, NB, GPU, and maybe even a HD in the loop as well. The only other thing I would have liked to see is the numbers for the 30RZ at 60Hz. It would put things into a little better perspective for those of us here in North America. It still only adds about 50W of heat but has a little better numbers.

Just my two cents.
Thanks for bringing it over here Stew, not all of us get to OCAU all the time.
Dave

All your suggestions are already on the cards for the expanded article, with the exception of NB and HD blocks, as it is my very strong opinion that cooling either is next to useless. With the data I'll be presenting, it should be pretty evident that such things don't really push the final results around all that much, as in there is a pretty strong case across a very broad range of scenarios that suggests that there is a fairly level plateau with respect to what makes a "good pump". I mean take a look at the Eheim 1048 vs the Iwaki MD-20RZ, there's hardly much difference (1.2C), and a couple of additional blocks don't suddenly chop flow rates in half, and even if they did, it still doesn't really affect the final rankings in a dramatic fashion.

What has the MOST impact on altering the final rankings of which pump is best for any particular person's scenario is in fact the radiator and the amount of cooling power it offers. This is the single largest impact item for determining which pump is best for someone's scenario, and not so much which blocks they have in the loop.

In any event, this will all come out in the full article that I'm working on. I'm still busy gathering more data and generating more graphs....

[Cathar]

Added the 60Hz MD-30RZ above.

Predicted in-line heat is 63W based on 50Hz MD-30RZ results.

Iwaki MD-30RZ @ 60Hz, 11.7 LPM, 0.038, 0.155 (estimated block C/W @ 11.7LPM)

Work out roughly to:

CPU = +15.5C above water temps, and Water = 163 * 0.038 = +6.2C, for a total CPU temp of +21.7C above the ambient air.

If we factor in that the pump is dumping all that extra heat into the room, the room would be warming up as well. Overall you'd be just as well off as with an Eheim 1250.

[Blackeagle]

The MD30Z @ 60hz requires a very large rad or dual rads for it to show any gains. Gets damned espensive at that point, as opposed to very expensive with a MD20Z....LOL.

I'd also like to see some pump figures where very large & low resistence heater cores are used. Chosen for very large size and ability to disapate high heat loads, they should help the bigger pumps out some. By large low resistence cores I'm thinking of the 2-342 as minimum and ones like the 2-192/GDI #399030 core which is huge.

And if the use of the Fusion GPU block were to sneak in I'd love it even more....

[Cathar]

Okay, the proposed radiator scenario was using a 120.2 with 2 x 30-35dBA fans on it.

If we consider say a 4 x 12cm fan capable radiator, with 4 x 35dBA fans on it, we would probably get a C/W vs flow curve like the 2 x 120.3 radiator show below (the pink line). The 120.3 in the plots below are assumed to have 30dBA fans on it, but if we assume 35dBA fans on our 2x2 radiator, then using the pink line is probably a pretty fair approximation. The HE radiators do have a very low pressure drop already, and a larger heater-core isn't going to change this much. The bulk of the pressure drop from heater-cores comes from the barbs/fittings, and not so much the internals.




Okay, so let's re-assess the 60Hz 20RZ vs the 60Hz 30RZ using those figures:

Iwaki 60Hz MD-20RZ, 8.7 LPM, 0.015, 0.159
Iwaki 60Hz MD-30RZ, 11.7 LPM, 0.014, 0.155

20RZ => 0.159 x 100 + 0.015 x 131 = 15.9 + 2.0 = 17.9C
30RZ => 0.155 x 100 + 0.014 x 163 = 15.5 + 2.3 = 17.8C

Factor in that the room would have a C/W itself of roughly 0.003 for a typical 3.5x3.5x2.5m office-sized room, and the extra 32W of the 30RZ makes the room 0.1C warmer than the 20RZ, and we're still back at pegging even once we factor in the increased ambient temperatures.

So you've gone and stuck in a 100W pump, a HUGE 4-fan radiator with 4 moderately noisy and powerful fans all at once, all added together for a total of 41-42dBA noise levels, and still even in this stupendously high-ended radiator scenario the MD-30RZ @ 60Hz only ends up just matching the MD-20RZ.

Talk about trying to drive a tack into two small pieces of wood with a jack-hammer...

Have been saying the same thing for well over a year now. There is absolutely NO point to ever consider buying/using a pump that is drawing over 50W of power, almost totally regardless of your situation. None - except in the very rare circumstance that you're drawing your water from a nearby flowing mountain stream, or using a swimming pool as a reservoir/radiator.

[Blackeagle]

OK, so much for the MD30.

Still like the idea of the large heater core to help with the added heat of the GPU as well as MD20 & CPU.

I'll be looking forward to seeing your article Cathar, I hope you're able to post it here. Sounds like a very good and informative one.

[jaydee]

Am I reading this right? There is .7C difference from the least powerful pump to the most powerful pump? Not even a 1C gain for over $100 worth of cost between the pumps? Or am I reading it wrong?

[Cathar]

Originally Posted by jaydee116

Am I reading this right? There is .7C difference from the least powerful pump to the most powerful pump? Not even a 1C gain for over $100 worth of cost between the pumps? Or am I reading it wrong?

Let's rank it for easier browsing shall we?

+20.8C => 2 x Swiftech MCP600 @ 13.8v (series)
+20.9C => Swiftech MCP600 @ 13.8v
+21.1C => Iwaki MD-20RZ @ 60Hz
+21.1C => 2 x Swiftech MCP600 @ 12.0v (series)
+21.2C => Iwaki MD-20RZ @ 50Hz
+21.4C => Swiftech MCP600 @ 12.0v
+21.4C => 2 x Eheim 1048 (series)
+21.5C => Iwaki MD-15R @ 60Hz
+21.6C => Swiftech MCP650 @ 12.0v
+21.6C => Iwaki MD-30RZ @ 50Hz
+21.7C => Iwaki MD-30RZ @ 60Hz
+21.9C => Eheim 1250
+22.3C => Eheim 1048
+23.3C => Eheim 1046

[Cathar]

For me it's a bit of a no-brainer, and it has to be the MCP600/AquaXtreme 50Z.

For 80mm/92mm/120mm heater-cores, the MCP600 is the pump you want to have.

For anything larger than a single BIX/BIP, grab a power-adapter for $30 and run the MCP600 at 13.8v. Even with much larger radiator setups all this does is bring the more powerful pumping solutions up to the MCP600 @ 13.8v's level, but they'll all be sucking so much more power to do so.

If Iwaki, or another company, made a 12VDC version of the 60Hz Iwaki MD-20RZ with the corresponding lower heat and more efficient DC motored operation, then that would be the one-size-fits-all pump with leading cooling performance for anything from a single BIP right up to a quad-fan monster radiator setup. The MCP600 @ 13.8v comes pretty close though. Just a little more oomph (~40% more pressure head) and it'd be absolutely perfect despite the small amount of extra power draw to do that. Problem with over-volting the MCP600 further is that it can't handle anything much more than 14.5v before the armature magnet "decouples" from the impeller and the pump stops pumping.

[jaydee]

Originally Posted by Cathar

Let's rank it for easier browsing shall we?

+20.8C => 2 x Swiftech MCP600 @ 13.8v (series)
+20.9C => Swiftech MCP600 @ 13.8v
+21.1C => Iwaki MD-20RZ @ 60Hz
+21.1C => 2 x Swiftech MCP600 @ 12.0v (series)
+21.2C => Iwaki MD-20RZ @ 50Hz
+21.4C => Swiftech MCP600 @ 12.0v
+21.4C => 2 x Eheim 1048 (series)
+21.5C => Iwaki MD-15R @ 60Hz
+21.6C => Swiftech MCP650 @ 12.0v
+21.6C => Iwaki MD-30RZ @ 50Hz
+21.7C => Iwaki MD-30RZ @ 60Hz
+21.9C => Eheim 1250
+22.3C => Eheim 1048
+23.3C => Eheim 1046

Interesting. Info I am definatly greatful for.

This is what my previous post was based on.

This now gives us a predicted correlation for the relationship between the final CPU temperature as affected by the flow rate, but more importantly also after factoring in the pump heat.

Eheim 1046, WB delta = 100W * 0.187C/W = 18.7C, Water delta = (100 + 1.5)W * 0.045C/W = 4.6C, Total CPU temperature = 23.3C above ambient
Eheim 1048, WB delta = 17.8C, Water delta = 103 * 0.044 = 4.5C, Total CPU Temp = 22.3C above ambient
Eheim 1250, WB delta = 17.2C, Water delta = 109 * 0.043 = 4.7C, Total CPU Temp = 21.9C above ambient
MCP600, WB delta = 16.9C, Water delta = 108 * 0.042 = 4.5C, Total CPU Temp = 21.4C above ambient
MCP650, WB delta = 16.8C, Water delta = 115 * 0.042 = 4.8C, Total CPU Temp = 21.6C above ambient
MD-15R, WB delta = 16.5C, Water delta = 122 * 0.041 = 5.0C, Total CPU Temp = 21.5C above ambient
MD-20RZ, WB delta = 15.9C, Water delta = 131 * 0.040 = 5.2C, Total CPU Temp = 21.1C above ambient
MD-30RZ, WB delta = 15.7C, Water delta = 150 * 0.039 = 5.9C, Total CPU Temp = 21.6C above ambient

[Etacovda]

Of course, this is with the cascade... id imagine temps would be different if someone was using a TDX instead.

[Ruiner]

This would make a nice front page article at overclockers.

[jaydee]

Originally Posted by Etacovda

Of course, this is with the cascade... id imagine temps would be different if someone was using a TDX instead.

True that. Different blocks have different flow curves but I imagine the difference wouldn't be greatly different.

[Cathar]

Originally Posted by Etacovda

Of course, this is with the cascade... id imagine temps would be different if someone was using a TDX instead.

TDX/RBX will be included with the final article.

Not a whole lot of difference between different pumps though - basically the same sorts of patterns as with the Cascade.

[Ruiner]

Do these trends persist with an extra 70 watts of gpu heat in the loop?

[psychofunk]

Originally Posted by Cathar

TDX/RBX will be included with the final article.

Not a whole lot of difference between different pumps though - basically the same sorts of patterns as with the Cascade.

Cathar could you add the more commonly available in the US MD20RLT model?

[Cathar]

Originally Posted by Ruiner

Do these trends persist with an extra 70 watts of gpu heat in the loop?

The information is there. Plug it in and have a look. Assume that the GPU block reduces the flow rates by 10% for any particular pump (crude, but probably a fair rough estimate for a moderate PD GPU block), add in 70W, and crunch the math.

GPU's won't dump 70W though, more like 50W, unless the GPU block is cooling the memory as well.

Higher heat loads does tend to make the impact of the pump's heat slightly less significant.

Okay - let's do a quick assessment:

MD20RZ @ 60Hz vs MD30RZ @ 60Hz, dual-fan radiator, etc, etc, 70W GPU heat.

60Hz 20RZ => 31W pump heat, 7.8LPM, 0.040, 0.162
60Hz 30RZ => 63W pump heat, 10.5LPM, 0.039, 0.157

20RZ => 100 x 0.162 + 201 x 0.04 => +24.2C
30RZ => 100 x 0.157 + 233 x 0.039 => +24.8C

As you can see, makes almost no difference.

[Delirious]

I just got my aqua extreme pump, which i based on cathars evaluation, and have to say its a very nice pump and is as quiet as my 1250 was.

[Cathar]

Originally Posted by psychofunk

Cathar could you add the more commonly available in the US MD20RLT model?

Guys - help me out here okay? The information is all there. Grab it, plug it in, munch the math a bit.

The 60Hz 20R offers slightly lower flow rates, ~8LPM predicted, than the 60Hz 20RZ (~8.7LPM predicted), but still dumps the same amount of heat.

The 20R is a worse solution than the 20RZ, but we're probably only talking about 0.1C differences. Unless you have a stupendously low PD system the flow rates aren't going to different much between the 20R and the 20RZ, and the rankings aren't going to change much, if at all.

[psychofunk]

Originally Posted by Cathar

Guys - help me out here okay? The information is all there. Grab it, plug it in, munch the math a bit.

The 60Hz 20R offers slightly lower flow rates, ~8LPM predicted, than the 60Hz 20RZ (~8.7LPM predicted), but still dumps the same amount of heat.

The 20R is a worse solution than the 20RZ, but we're probably only talking about 0.1C differences. Unless you have a stupendously low PD system the flow rates aren't going to different much between the 20R and the 20RZ, and the rankings aren't going to change much, if at all.

Ahhhh, I just noticed the info is right there on the 1046, easy enough for even me to get . Thanks

One other thing Cathar. Looking at this information here it would look to me to be better to have 2 seperate loops, one for CPU and the other for GPU as opposed to a single loop with 2 blocks. Am I off in my thinking?

Okay just one more "one more thing" can that $60 power adapter deal power two mcp600's or would I need 2 of those adapters?

[JWFokker]

I understand there are a lot of variables to be considered here, but what if you were to use a larger radiator and maybe a fan cooler pump?

I'm not talking anything disgustingly huge. Well, maybe it is:

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

But for $60 shipped how can you argue with the ability to mount 9 120mm fans? And it's solid copper too!

And the pump:

http://www.premiumaquatics.com/Merch...gory_Code=MAK4

It's slighly less powerful than the Iwaki MD30, 14ft head instead of 16ft, but what makes it exceptional in my eyes, is that it uses only 65W and it's fan cooled, instead of water cooled like most pumps. The only thing I question is it's unknown reliability. In your estimation, would it be worth it to investigate fan cooled pumps instead?

Regardless, I'm probably going to order both Friday night or Saturday anyway, unless the pump is notoriously unreliable.

[JWFokker]

Perusal of some aquarium forums indicates the Mak4 is a pretty decent pump, but somewhat noisy, though the one I'm looking at is one of the smaller models. It's quieter than an Iwaki of comparable power but doesn't have the same reputation for quality. Blueline pumps however do look quite good, equal in performance to an Iwaki, but slightly quieter and definitely cheaper.

But I've come to the conclusion I can get similar performance for WAY less just by buying another Mag 3 and running it in series.