does the thickness of a *water block matter?

[jayhall0315]

No offense guys, but many errors in this thread. The transfer of heat follows the second order partial differential Heat Equation anisotropically and follows as such at boundary layers. And the most important qualities are surface area for thermal transmittance and turbulence (Reynolds number from ~3500 to 4500 is best for copper blocks). In so much as the block has enough copper to maintain rigidity when compressed is all that is needed. Theoretically, the best copper block is one that would be only one layer of copper atoms thick with maximum surface area for kinetic transfer. The reason is that the copper is acting as a 'thermal transfer wall' and not a thermal storage container. Rapid diffusion is needed because the hydrogen bonds of water conserve heat much better than the tightly packed atoms in a copper lattice. And this is the reason for the three times larger specific heat capacity (the critical term) of water. And as such, the copper block only acts a transmitter of kinetic energy at fairly high efficiency (about 400 W/ m K). So the optimum block is one that spreads out in size very quickly over the cpu but is still very thin (minimum mass needed for rigidity without bending under clamp stress) and that maintains maximum surface area thru vectored pins to produce a transitionally turbulent flow (about Reynolds number 4000). On a 3d graph, this surface area vs size vs thickness plot is optimized at the location where the partial derivatives = 0 (the top of the 'hill' so to speak).

Ideally, what would be best is to just run water directly over a finned CPU head made of copper that connects directly to the silicon layers. In real life, this would be to difficult for the home user and a major cause of short circuits, but Intel did look into this idea in the late 1990s with the Itanium brand for server stuff. The reason copper is not used today for the CPU shell is rigidity and electron interference with the transistors below.

-Jay

[the9093]

jay, sorry i took apart what you wrote. it makes a lot of sense. thank you for that.

"Theoretically, the best copper block is one that would be only one layer of copper atoms thick with maximum surface area for kinetic transfer."

"So the optimum block is one that spreads out in size very quickly over the cpu but is still very thin (minimum mass needed for rigidity without bending under clamp stress) and that maintains maximum surface area thru vectored pins to produce a transitionally turbulent flow (about Reynolds number 4000)."

"Ideally, what would be best is to just run water directly over a finned CPU head made of copper that connects directly to the silicon layers."
-Jay

i'm waiting on a d-tek fuzion v1. hopefully i'll get it by saturday. then i'll do a semi-official comparison against my modded storm / g4. i'm hoping to get better temps with the fuzion so as not to feel dumb for wasting my money. :fingerscrossed:

[the9093]

got the v1. don't like the design. will return.

[warriorpoet]

...also thought of the fact that the swiftech gtz gets really good temps. it has small pins in the block which allows heat to transfer and quickly be cooled because of the smallness of the pins and a thin contact point to heat source. ...

2 things make that block:

1. H2o turbulence at point of thermal transfer
2. surface area of pins (more= greater surface area)

For the extreme of 2. see the Swiftech GTX, for the extreme of 1. see G4/ Storm.

[warriorpoet]

got the v1. don't like the design. will return.

The design of that particular block set off a revolution in waterblocks. The only possible improvements I can think of are:

1. addressed in v2 (midplate leakage)
2. mounting mechanism
3. improper contact area for i7
4. REALLY addressed with a Fitseries3 top (choked outlet, midplate leakage)

[the9093]

2 things make that block:

1. H2o turbulence at point of thermal transfer
2. surface area of pins (more= greater surface area)

so in essence water blocks work work by creating air pockets as its faster to cool water molecules in the air. that's why turbulence is needed?

[Jah]

so in essence water blocks work work by creating air pockets as its faster to cool water molecules in the air. that's why turbulence is needed?

No you want turbulence to increase the number of water molecules that get in contact with the block. If you have a laminar flow a larger number of water molecules will just pass through the block without absorbing any/very little heat.

Turbulence and surface area is just two different ways to get as large part or the water passing through the block to get in contact with the block to absorb heat as possible.

[the9093]

with a borrowed fuzion v1, here's my temperature comparison. earlier i mentioned my idle temps were at 22*C/72*F after modding my swiftech storm rev 2. this time the idle temps were at 25*C/77*F. this must have been because of the ambient temp.?
for these tests the ambient temp stayed at 21*C/70*F. two tests on my e6300 65nm cpu. at default 1866MHz and overclocked at 3360MHz, C1E and EIST were disabled at both speeds. one mounting for each block. i considered the mountings good when the temp of both cores stay the same, readings using realtemp v3.4. everything in the single cpu loop stayed the same, 3/8" tubing and the mcp665 non-vario pump using 1/2" high-flow barbs. prime95 was used for burn-in. custom in the torture test options, min and max fft size both at 8K and run FFTs in place checked. burn-in ran for 20 minutes, that was about the time with a very slow rise in temps or not at all. a change between block temps were in no way significant. with default cpu speed there's only a degree less in favor of the fuzion. as with overclocked temps the fuzion was a degree better at idle. at load the fuzion was not a whole two degrees better than storm. even though i would've liked to, there was no way for me to check things like pressure drop and flow rate. as i don't have the tools for that.

swiftech storm:

1866MHz
idle:25*C / 77*F
load: 35*C / 96*F
3360MHz
idle:31*C / 88*F
load: 53*C / 128*F

d-tek fuzion v1:

1866MHz
idle: 24*C / 75*F
load: 34*C / 93*F
3360MHz
idle: 30*C / 86*F
load: 51*C / 124*F

i'm convinced my mods on the storm allowed me to be content with what i have and have made. while not having to upgrade to a block i won't need. i'm guessing until i know more about water cooling.
bellow is a better picture of the modded storm. providing excellent temps. for my needs. i'm thinking of removing the middle plate, the one on the right. maybe it'll give even better results, its worth a shot.