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General Liquid/Water Cooling Discussion For discussion about Full Cooling System kits, or general cooling topics. Keep specific cooling items like pumps, radiators, etc... in their specific forums.

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Unread 03-31-2004, 12:07 AM   #51
Cathar
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Quote:
Originally Posted by Les
Does your simulation predict better cooling directly under a "cup"?
My crude models using heatspreading and convection coefficients give little enlightenment.
Think that a detailed analysis(including convection profile) by programs like TAS may be necessary to answer even that simple question.
Like Bill says, it's a bit of a mystery even to me. I can plug values in for h based upon observations, and reckon I might have an idea, but h is not something that I'm mathematically determining. Basically it's a process of "do some theory", build a block, measure it, revise the theory, make changes, and repeat.

I'm fairly confident that for lower flow rates (<4LPM) that the areas immediately under the jets where stagnation occurs are the hottest sections. At higher flow rates I believe that behavior slowly changes, but that perhaps the ratio of jet diameter to bp thickness is still perhaps a little too low. I also believe that there's also a small issue with the triangle cross-over between 3 adjacent cups at lower flow-rates, which is another thing that's changed on the XXX.

I think the main issue here is that h is varying very widely depending on both the flow-rate, and the actual location within any one cell, which of course is fairly obvious given jet theory, but I guess what I think I didn't anticipate is the magnitude of the effect that it is having on CPU overclock stability, which has caused me to re-think my strategy on ultra-thin (<1mm) bp's.
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Unread 03-31-2004, 12:17 AM   #52
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Some piccies of the first-cut XXX prototype next to a regular Cascade. Note, neither block has been cleaned up after machining so they look a little messy.





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Unread 03-31-2004, 12:26 AM   #53
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Quote:
Originally Posted by Cathar
... I can plug values in for h based upon observations, and reckon I might have an idea, .......
It impossible to get a value of " h based upon observations" with no true DeltaT or W and an assumed C/W(TIM).
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Unread 03-31-2004, 12:40 AM   #54
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Quote:
Originally Posted by Les
It impossible to get a value of " h based upon observations" with no true DeltaT or W and an assumed C/W(TIM).
You can determine where h is roughly at on an average. Is it exact? No. I didn't even begin to claim that it was. 'tis all theory and approximation until nailed down by someone with substantially more research funds and time than I have.
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Unread 03-31-2004, 12:47 AM   #55
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whew
gonna need a filter on that puppy
the Cascade I tested was filthy when I borrowed it, and I'll be damned if it was not somewhat dirty after I finished - and I have a 20 micron filter
-> high performance has high requirements
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Unread 03-31-2004, 01:17 AM   #56
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Quote:
Originally Posted by unregistered
whew
gonna need a filter on that puppy
the Cascade I tested was filthy when I borrowed it, and I'll be damned if it was not somewhat dirty after I finished - and I have a 20 micron filter
-> high performance has high requirements
I've actually found that the Johnson/Jabsco in-line strainers to be pretty effective. I fill my loop with water that's been fed through a 10 micron filter first anyway, and so long as the loop was clean initially the blocks remain fine.

Still though, yes, "micro-structure" blocks do place a very high requirement for a clean system.
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Unread 03-31-2004, 01:23 AM   #57
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Quote:
Originally Posted by Cathar
You can determine where h is roughly at on an average. Is it exact? No. I didn't even begin to claim that it was. 'tis all theory and approximation until nailed down by someone with substantially more research funds and time than I have.

Here suggested some "possible h"s for the WW.
However with Kryotherm only dealing with channels am unable to do the same with the Cascade.
Some rough numbers would be interesting.
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Unread 03-31-2004, 01:47 AM   #58
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Quote:
Originally Posted by Les
Some rough numbers would be interesting.
Rough average estimates only for h for Copper Cascade.

h =~ 80000 at 10LPM
h =~ 55000 at 5LPM
h =~ 30000 at 2LPM
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Unread 03-31-2004, 01:55 AM   #59
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Ta
Seem in keeping with Flomerics based guesses.
Wonder what TAS would make of them.
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Unread 03-31-2004, 02:07 AM   #60
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what are you guys doing ?
a nominal device average is worthless
h is location specific and different also per the conditions
this is what the gridding and nodes are all about
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Unread 03-31-2004, 02:16 AM   #61
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Point taken, but this an average within a cup.
There being 50+ cups per device, it may be a starting point.
Only this guy's opinion.
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Unread 03-31-2004, 02:47 AM   #62
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perhaps, but this touches on my heartburn with CFD for wbs
sure, one can sim a cup, test, correct, and validate
but this does not address the cups' interconnection necessary for any device calc;
nor, more importantly, does it enable 'looking' at the effects of cup changes (of any sort I suspect)

yea, perhaps better than nothing - but for me not worth my time if not predictive
Flotherm is very capable for many things, but I have reservations about its abitity to model mbs w/o extensive parametric validation
if I have to pay $28K pa per seat for Flotherm, plus a pHD to run it; and then STILL have to test 'till hell freezes over to validate, . . . its cheaper to build and test
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Unread 03-31-2004, 09:48 AM   #63
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Cathar,

No material expert here, either. In going through my book I find that the electrode potential differential from copper to silver is ~0.5V, copper to chromium (stainless surface chromium dioxide) is ~1V, and copper to aluminum is ~2V. All this is at 25°C.

From what you described of that pump, I'm reasonably confident it was a matter of contamination. Nonetheless, if contamination is likely in a typical system then I'd agree stainless ought to be avoided, especially in extremely narrow passageways.
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Unread 03-31-2004, 08:05 PM   #64
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Quote:
Originally Posted by myv65
Cathar,

No material expert here, either. In going through my book I find that the electrode potential differential from copper to silver is ~0.5V, copper to chromium (stainless surface chromium dioxide) is ~1V, and copper to aluminum is ~2V. All this is at 25°C.

From what you described of that pump, I'm reasonably confident it was a matter of contamination. Nonetheless, if contamination is likely in a typical system then I'd agree stainless ought to be avoided, especially in extremely narrow passageways.
Would this affect my system much? Metals in contact with water = brass, copper, silver. Ive not noticed any corrosion yet but I dont want 0.5v coming from the waterblocks. Also note the silver is not touching any other metal in contact with water.
Maybe this would be god for a new thread, on corrosion testing? If someone could deisgn a test for corrosion, that could be done accuratly, I do have silver, brass, copper, steel, and alu I can test with.

Cathar your xxx block pics look like they will be great performers. Could I have a XXX-SS block once you start making them (Ill supply the silver, got plenty here )
Also how much more jets do you think will be possible to add into that small an area?
Any plans to make GPU versions?

Will you continue making blocks once youve desiged something better for non-reseach purposes (if you ever did?) or will the old designs either get discontinued or licenced to other companys for manufacture? (like D.Tec/WW).

Last edited by |kbn|; 03-31-2004 at 08:14 PM.
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Unread 03-31-2004, 11:08 PM   #65
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|kbn|. In a standard water-loop copper/brass/silver are basically galvanically unreactive with each other. The silver->brass difference is pushing it somewhat, but it is basically safe for long periods (many months -> years). At least that's what I've been able to ascertain on-line, and having run a copper/silver/brass loop totally unprotected in terms of corrosion inhibitor for about 6 months now the silver has only just started to develop a mild discoloring, which is about the sort of reaction level I would have expected.

The XXX blocks I only intend to make in silver for the bases. Am giving very serious thought to putting copper tops on them though just for strength as I don't really want to risk another repeat of a bad polycarb batch resulting in cracking tops. This would also allow the block to be thinner, as in 16mm high instead of the current 20mm.

Am giving serious thought to calling such blocks "Cascade XS", and dropping the XXX code-name moniker.
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Unread 03-31-2004, 11:17 PM   #66
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Quote:
Originally Posted by Cathar
Am giving serious thought to calling such blocks "Cascade XS", and dropping the XXX code-name moniker.
Damn, now the "I'd hit that" joke when you post pics of the finished product isn't going to be nearly as funny.
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Unread 04-01-2004, 01:23 PM   #67
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When I took out my silver gpu block it had no noticable change in colour. I had been using it for a month or two.

Cathar as silver is a lot more expensive than copper, and that the acctual cooling area in your block is ~30mm2 at most? You could do what I intend to reduce the cost some what.
My dad has made the silver into 20mm squares 8mm thick and they are accuratly made. We intend of fitting the silver into accuratly made copper blocks so that we get the advantage of silver, but without the cost. If this could be accuratly done on the scale you intend without problems of the jets/ cups not lining up, I think it would be a good idea and make silver blocks more affordable. They just wont look as shiny - silver is very easy to get a very nice shine.
Silver will perform better but would depend a lot on the deisgn to take advantage of it, I look forward to any test results from this new block in both materials.
some people might still want 100% silver bases though.
Copper tops would be nice, (none of this annodised alu crap ), but plastic may be best for your design. I recommend non brittle plastics like polyethelene instead of accrylic, never used poly carb though.

XS is a nicer name than XXX-SS
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Unread 04-01-2004, 02:41 PM   #68
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It will be interesting to see how this new block compares to the original with half the jets blocked off, when used on an athlon xp. Any estimate on how the pressure drop will compare to the original?
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Unread 04-01-2004, 03:25 PM   #69
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Which code are you using and how small do you want your capillaries?

Quote:
Originally Posted by Cathar
|kbn|. In a standard water-loop copper/brass/silver are basically galvanically unreactive with each other. The silver->brass difference is pushing it somewhat, but it is basically safe for long periods (many months -> years). At least that's what I've been able to ascertain on-line, and having run a copper/silver/brass loop totally unprotected in terms of corrosion inhibitor for about 6 months now the silver has only just started to develop a mild discoloring, which is about the sort of reaction level I would have expected.

The XXX blocks I only intend to make in silver for the bases. Am giving very serious thought to putting copper tops on them though just for strength as I don't really want to risk another repeat of a bad polycarb batch resulting in cracking tops. This would also allow the block to be thinner, as in 16mm high instead of the current 20mm.

Am giving serious thought to calling such blocks "Cascade XS", and dropping the XXX code-name moniker.
Which finite element code are you running? ANSYS? or NASTRAN? OR ? and have you considered using self assembled or lithographically etched tubes?
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Unread 04-01-2004, 05:21 PM   #70
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Quote:
Originally Posted by talcum
Which finite element code are you running? ANSYS? or NASTRAN? OR ? and have you considered using self assembled or lithographically etched tubes?
I am using a concoction of my own writing. I suppose it could be classified as a finite-element analysis tool, but it's horribly primitive by modern day professional standards and has no fancy visualisation tools. Best bit though is that it is free, apart from me spending some time to code it up.

Self-assembled?

Have discussed lithographically etched tubes with someone. Biggest issue appears to be that everything needs to be squarish.
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Unread 04-01-2004, 05:31 PM   #71
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All you need is a synchrotron.....

Quote:
Originally Posted by Cathar
I am using a concoction of my own writing. I suppose it could be classified as a finite-element analysis tool, but it's horribly primitive by modern day professional standards and has no fancy visualisation tools. Best bit though is that it is free, apart from me spending some time to code it up.

Self-assembled?

Have discussed lithographically etched tubes with someone. Biggest issue appears to be that everything needs to be squarish.
No - I mean self assembled nanotubes using a mask and PMMA like the big boys.

My issue seems to be that we're talking 10-50 nanometers for the tube using self assembly and more for a mask like that used for the wafer.

Maybe I can try something at this end.

-talc
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Unread 04-01-2004, 05:52 PM   #72
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Quote:
Originally Posted by talcum
No - I mean self assembled nanotubes using a mask and PMMA like the big boys.

My issue seems to be that we're talking 10-50 nanometers for the tube using self assembly and more for a mask like that used for the wafer.

Maybe I can try something at this end.

-talc

Nanometers? We're still dealing with hundreds of microns here.

Big boys? Sorry, doing what I can on a budget that amounts to around $1500 US max.

Happy to know if there's some way to do things better though.
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Unread 04-02-2004, 04:32 AM   #73
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Quote:
Test 2) Thicker bp Cascade (essentially a copper Cascade SS without jet mods) => Overall CPU temperatures slightly higher and overclock stability was about the same at higher flow rates. Better overclock stability and better temperatures at lower flow rates than regular Cascade. Hypothesis: thicker bp provides a better "smoothing" effect.
Cather, at the risk of stating the bleedin' obvious. The "smoothing" effect of a given volume of copper must be related to it's heat capacity. Coppers heat capacity is less than that of water but not by a huge amount when stated relative to volume (4.2ish vs 3.5ish J/cm^3.°K).
That said, water IS better, by 15-20% so the more water in the vicinity the better the dampening must be. i.e. the thinner the baseplate the better. The dirty big fly in the ointment is the TIM-BP-H2O thermal resistance, which might nullify any benefit, leading to, thicker BP must be better, above a certain thickness.What that thickness is I don't know, it might be near zero. A direct die cascade would be interesting. ie no cup bases, the base of the "cup" being the surface of the CPU die.
What I am say is that I am concerned that all the tests showing that direct die cooling gives higher temperatures may be missing the point. The, lets call it "Maximum Attainable Stable Frequency/°C", might in fact be higher, thanks to the high specific heat capacity of water, even though the actual cpu temp could be higher. What the WW and than Cascade showed for me was that mass of copper (or silver) is not important for maintaining good temperatures. What is important is the way the water is delivered to the hot area. Deliver it in the same way direct to die and I can not see how it could be worse.
I am not a direct die advocate, actually I've thought it inferior because of the necessarily smaller surface area, but with impingement in the equation and your observations of overclock stability, I am beginning to wonder.

Cheers

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Unread 04-05-2004, 08:05 PM   #74
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I happen to have page 5 of this thread from before the crash still open. I'll repost. I hope no one minds. Unfortunately, those spiffy diagrams of cup bases and discussions of such were on page 4.

Quote:
Originally Posted by Cathar
Yes, the challenge is truly in the machining. Can think up of whatever, it's making it that's the hard thing. The real challenge is in making machinable reality meet with superior performance design.

The jets are 0.95mm OD and 0.55mm ID.
Quote:
Originally Posted by Stang Man
what kind of machine are you using, an EDM??!
Quote:
Originally Posted by Blackeagle
Cathar,

I really like the idea of a modified Cascade with cup bases along the lines of what Murray 13 posted. But why not a cup that is a cross between Murray's fig. #1 and #3, a raised peak in the center, but with squared off base to wall like in the basic Cascade cups. It would seem to me that this would offer a greater surface area, but also a better impingement aginst the walls of the cup than what a curved base offers. I will grant the fully curved base of the cup may well offer lower flow resistence however.

Even a 1-1.5c gain over the SS Cascade would be a nice bit of work when considering how far you've pushed designs already.

I think you have little to feel humble for, without your White Water & Cascade designs I suspect we'd still be looking to the TC-4 as a top performer. The new Cascade XS should be very interesting. Congrats to you once again for pushing the boundrys ever farther, as I have full faith that the new base configuration is going to be another winning design for you.

I can forsee buying a Cascade XS from you if you offer them for sale. Please do offer them for sale, pleeease. And if offered only in Ag you shouldn't be as overwhelmed with orders for this design like with the Cu White Water and Cascade blocks. So the XS won't cut into your time for your familly.

Congrats once again, and I look forward very much to seeing the results of the alternative design.
Quote:
Originally Posted by Les
Do not forget Volenti.
Would be perilous to overlook his min-channeled work.
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Originally Posted by Cathar
A CNC mill
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Originally Posted by Cathar
Now you are getting close to what I've drawn up for the second prototype.

The #2 proto block can be machined almost entirely with a 2.0mm mill bit for both the base and middle plates. If it works then total machine time will be cut roughly in half in comparison to a regular Cascade, for slightly better performance. Time will tell....
Quote:
Originally Posted by Les
Quote:
Originally Posted by pauldenton
cheers - i think the colour jumps were throwing me..... so the (modelled) "h" for the 9fin/8channel block ranges from 50000 at 1 LPM to 130000 at 10 LPM ?
and the 25fin/24channel one from just over 90000 at 1 LPM to about 195000 at 10 LPM?
Yes and yes.
Quote:
Originally Posted by Stang Man
how are you managing cutting that lexan without snapping the jets, what kind of endmill you using?
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Originally Posted by Blackeagle
Didn't mean to slight anyone Les.

But I find the ideas being discussed regarding modifications to the base of the cups very interesting. Cathar has been working with the jet side of the Cascade design a good deal already, now he's starting to rethink the cups base design as well. A combination of the larger surface area in the cup bases and a optimised number of jets should prove to be of real interest as to how much more Cathar manages to squeeze out of ambient temp cooling. And I think that there may well be more to be found in the Cascades base, rather than to try to find ways to make the jets smaller, at the cost of machinability of the design.

I don't see how he can gain much more in actural temp improvements, but along with a extra 1-1.5c, the gains to O/Cs will be a better messure.

And if Cathar finds a new cup & jet balance that both improves performance even beyond the SS Cascade's while still being reasonablly machineable then Cathar will again be pushing the industry as a whole to improve it's product lines again, as thiers will be held up for comparrison with the top block known, the Cascade XS.

I just hope this time around the industry actually innovates, rather than just copy Cathar's work.
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This last portion of this post may be hope'n for a lot I know!
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Unread 04-05-2004, 09:00 PM   #75
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Thank God someone managed to save page 5 at least! Sad we lost page four, but perhaps we can resume the thread from here.

Great job guntledweasel! !

Man!, I can hardly wait to see the results of the next prototype comparisson of the two alturnatives for advancing the Cascade XS design.

Now I have to admit I'm sort of glad I missed on the last order of SS Cascades. Now I'll be able to afford a Casscade XS instead.
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