it would be interesting what the figures are like with the 10W pump you initially used
0.1C difference doesn't seem all that much if you jump to IwakiI am not sure what you mean there though????? Is that a proportional measure or actual difference?
it would be interesting what the figures are like with the 10W pump you initially used
0.1C difference doesn't seem all that much if you jump to Iwaki
Yeah, I use 16% efficiencies in my calculations when mapping from hydraulic power (restriction x flow) to estimated required pump power (power draw). I then multiply that value by 0.9 to arrive at the pump heat dump directly into the water. This is all in the estimation stage.Originally Posted by serialk11r
A DDC2 is 18-20W. At a 90% water heat dump, 2W is going into the bits not touched by water. Hook up a common DC electrical resistor to a DC power supply, and feed 2W of power through it. Wait 1 minute and touch it, and let me know if it doesn't dang near burn your finger off. That's the sort of heat that you're feeling from the bottom of a DDC. Blow some air over it and it'll feel cool all the time. Most pumps sit on their bottoms with no air-flow. Give anything small 2W of heat load and sit it where it gets no air-flow, and it WILL get quite warm.
Yer typical high-performance GPU ram chip generates around 2W of heat when under load. Touch one without a heatsink on it after its been working away for a while and you'll just about scorch your skin.
Remember, temperature != heat.
Last edited by Cathar; 06-12-2007 at 05:06 PM.
Yeah but what I'm saying is the housing is plastic...and all plastics are poor conductors of heat. Anyways I understand this is all in the estimation stage and stuff.
Well anyways enough off topicness :P
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Add ~0.3C to the CPU, ~0.5C to the GPU pretty much across the board when compared to the DDC2.
Your CPU and GPU will be ~0.1C cooler when using an Iwaki RD30 as opposed to a top-modded DDC2, is what I meant.0.1C difference doesn't seem all that much if you jump to Iwaki
Great work! So even as heat load and an addition of a block, the results still vary very little (say that 10x!) I would have thought that with the addition of both more restriction and the addition of a higher heat load, the larger ID tubing would have shone though. Apparently I was mistaken!
Even if it is theoretical data + fudge, I still think that there is enough accuracy in the program that the real-world tests would come to within, say, 3-5% of the theoretical. Great work, my friend
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Plastic conducts heat poorly, and thats just the problem. The air in the pump PCB section will be getting hot 'cos the heat can't escape 'cos of the plastic surrounds. Eventually the plastic surrounds will warm up a fair bit due to the temperature of the air inside the pump. If you insulate something well enough, it doesn't matter if you give it 0.1W of heat-load, it will continue to get hotter and hotter if the heat can't escape to somewhere else.
With such a small heat gain from the Iwaki the RD30 is looking even more appealing from a reliability standpoint.
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Great data Cathar! I *do have to wonder, however, why this kind of testing wasn't done by companies (I'm aware that Swiftech has kept 3/8" around, but they still haven't advertised the difference, or lack there of...), who spend a lot money developing and selling this kind of technology...makes ya' wonder
Anywho, this is GREAT news for the 'small' future of computers; as more and more people start using SFF cases, tighter bend radii will be needed, and now that we *know there isn't much of a difference, it'll make the transition that much smoother
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i guess the only reason you'd want an Iwaki is for reliability (so they say) lol
those differences are so minuscule it's mind boggling
i am learning today
I thought about going to an rd30..but after contemplating going through the hassle of getting a meanwell converter and mounting it..etc...the ddc2 was more appealing,smaller,and a helluva lot easier to deal with..
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This is great data provided by Cathar and should bring a sense of calm regarding the "high flow / low flow" fights on multiple forums.
Tis a very slippery slope what you ask. First, people as a whole do not trust mfgr data - this is just fact. If company xxx came in here and said what Stew said, they would likely be laughed out of here and the thread closed in short order. There is one mfgr in particular (won't mention names) that presents VERY good data that is often balked at - I have been guilty of this myself. This company has been very discouraged at times of this attitude (and rightly so IMO) and has seriously considered releasing no data whatsoever (would be a mistake IMO). So you see, the mfgr's make their wares and it is up to (IMO) the unbiased users with a brain (see Cathar for example) to decipher the crap from the good.Great data Cathar! I *do have to wonder, however, why this kind of testing wasn't done by companies (I'm aware that Swiftech has kept 3/8" around, but they still haven't advertised the difference, or lack there of...), who spend a lot money developing and selling this kind of technology...makes ya' wonder
Anywho, this is GREAT news for the 'small' future of computers; as more and more people start using SFF cases, tighter bend radii will be needed, and now that we *know there isn't much of a difference, it'll make the transition that much smoother
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hold the phone. this means the PA120.2 and GTX pressure drops weren't factored in....so all the data would be different...right?
yeah i asked that, and you replied you copied it exactly from the website, but it is the tubing curves that you altered, not the DDC curve. the DDC curve also must include the pressure and flow drops to obtain the correct data
Why would I want or need to alter the DDC curve?
Because those figures will not be the same with the parts used
The DDC curve operates against some level of restriction. I factored the current 3/8" fittings on the pump into the system restriction curves. When I modelled the different fitting types, I can determine the impact in one of two ways:
1) Alter the pump's PQ curve based upon the fittings on it
2) Factor the fitting impact into the system's PQ curve, and intersect that with a constant pump PQ curve.
There may be very marginal variations between the two, but as I said, the nature of the shapes of the curves is such that any variations impacts everything roughly equally.
It's just easier to do #2.
ok i guess i see now. thanks for explaining yourself
...mmmkay... was this some random guesstimate that I happened to have mentioned over AIM or something (likely based on testing that Lee did)? Because, up until just now (since you brought it up), I hadn't run the calculations with my own data (which has already been published in XS).
After doing a little graphing and some rough calculations, I came to the following (all at peak pumping power):
Stock DDC-2: ~17% efficient (~3W max pumping power, ~18W total consumed)
Stock DDC-3.2: ~13% efficient (~2.1W max pumping power, ~16.32W total consumed)
DDC-2 w/DDCT-01s top: ~21% efficient (~4.25W max pumping power, ~20.64W total consumed)
DDC-3.2 w/DDCT-01s top: ~19% efficient (~4.2W max pumping power, ~22.32W total consumed)
The pressure drop incurred by the components used doesn't change the overall performance characteristics of a pump (there's a reason why you see intersecting curves in the first graph that Stew posted... The red curve represents how the pump performs (flow) at all head pressures attainable by the pump, the other curves represent the pressure drop of the cooling components used vs. flowrate, and the point of intersection represents the head pressure at which the pump operates and flowrate the pump attains given the components attached to it).
Hopefully that'll clear things up a little for you.
Anyway, interesting information, Stew...
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there we go! thats just what i needed, thanks a ton. and again, amazing info cathar
Yeah the point at which push comes to shove, as it were.
Petra you brought that efficiency thing up about 4 months ago or so, when I made my rant thread
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A half-baked guesstimate that I actually posted? Hmm... I blame your rantPetra you brought that efficiency thing up about 4 months ago or so, when I made my rant thread
Last edited by Petra; 06-12-2007 at 08:46 PM.
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Got a correction to this. Checked the code and I'm actually using a 17% assumed efficiency in the software estimator. I forgot that I had changed it a while back.
It's fairly rare that a pump is operating exactly at its BEP (Best Efficiency Point) in any setup, and that's why I had chosen a value of 17%, which provides a guided value that more closely approximates what will happen in reality across a broader range of scenarios.
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