Lookie what I just got
 

it's a 1U rackmount p4 heatsink, see if you can guess what I'm going to do with it :D

OK, I'll be the first to guess:)
You are going to encase it with a copper cover soldered in place (if the screws shown in the picture are the mount hole positions then them are some large barbs).

correct:D their 1'' barbs actually. I have a bit of mucking around to do on the ends to try and distribute the flow a bit, but it isn't going to hurt to have most of the flow going through the middle part of the block, if some of the outside fins get bugger all flow I'm not going to loose any sleep over it.

Other than the fin area being a little too large (for water cooling), I can't see any reason why it won't perform exceptionally well.

Is that a skived copper heatsink?


If so, I was looking for a HS exactly like that one!!

Where'd you get it? Or list a name so I can Google :D

yes, I got mine through a local supplier, the heatsink web site is here

either that is a lot of dence fins or its the base... waht is it?

it isn't very clear in that pic, here's a better one showing the fins.

the blurry ruler in the foreground is metric

With high pressure, I think you may have a good idea ... keep us in tune.

This isn't a skived fin HS, but it's very nice! What's your watercooling conversion plan?

first your gonna cut out the area below the barbs so it can go to all fins rite? ten your gonna make it copper rite? the rest of it? i hope so. this thing will be mad cool!

hmm, I was under the impression that it was, I thought that was the only way they made these thin fin heatsinks?

oh yea I'm working on it this weekend (going to get some bits for it very soon in fact) I'll post update shots as I go, though for the moment I may only go with 3/4'' barbs sinse I still havn't got my 1'' plan sorted out yet, 3/4'' will be a lot easier to temporally set up.

It won't be easy to get enough water between those fins.

I have a heatsink almost just like that.... well not anywhere near like that now that I look at it. Its a xeon heat sink. Would make a cool water block, except that its copper and aluminum. Bigger then any heatsink I have ever seen.

One place to find a 1U copper sink
 

www.rackmountpro.com carries these, but they're $20/each and the shipping prices are horrendous.
They also carry one for an Athlon, which seems to work pretty well (for a 1U HSF on a Duron 1300...)

And not to contradict bigben2k, but it looks like it is skived, I know the Athlon ones we've got are, and the pic above certainly looks very similar.

Ok I've done my shopping and have a length of 3/4'' hard drawn copper pipe (that I'll flare and use as hosebarbs) it has an internal area of 227mm/2, after attacking the heatsink with a ruler and some educated guesswork on the thickness of the fins I've come up with a "channel" area of 432mm/2.

That's actually ideal for the 1'' I was originally planning, but I don't think I'll have room for the geometry needed to get that flow too all the fins properly, so 3/4'' it is. However since I don't want to have the water flow slowing down in the block (re; water block theory) I'll direct the water flow through only the centre of the block, through a roughly equivilant fin area. like so;

this also has the benifit of greatly simplifing the construction, something I won't be complaining about:D

and here's the results after trimming the "un-needed" fins off

just curious, how did you trim off those extra fins? it looks very even, like you took a mill or something to it..

I may not have the right understanding of "skived", but anyways...

You're on the right track. The challenge is going to force the flow between the fins, and that's going to mean keeping the lid right on top of the fins, or at least very close.

At this point, you've probably already thought about some kind of manifold, to allow the water in and out. In one side, through the fins, and out the other. Right? Right...

no milling involved, I simply used a hack saw (carefully) and cleaned up a bit with a file.


Oh yea, that's pretty well exactly what I'm doing, the water won't have any choice but to go through the fins , it doesn't show up very well in the pictures, but the fins are very thin, they are only a quarter to a third as wide as the gap between each fin.

anyway I've been a bit generous with the flow passage to try and compensate for any friction or weird boundary layer based flow restriction, I should have it finished today so we'll find out :D

how many fins does that thing have? like 100 on each side?

that should be an ultra cool block, lets just hope you can seal it all ok

it originally had 78 fins, it has about 58 now (cut 10 off each side)

everyone loves pictures, picky time:D

parts layed out ready for assembly;

The reason I asked about this is because I had basically the same idea - I asked about a HS like this in the HS area, but no one knew of one :( It was either this or another solid block design I came up with.

I figured I'd have the barbs enter into a chamber that would feed into the fins. I'd put a knife edge on the ends of the fins to lessen restriction.

In my opinion, the pic with the fins on the sides cut off should work good for a block sitting on the CPU. I think you could use more/all of the fins if you were going to go with a Pelt setup.

block assembled and tied together with wire;

block after soldering, leak free first go:D

good vertical shot down the tubes showing the fins and spreading chamber inside.

A quick flow test with my 2800L/H pump through 1m of 3/4'' hose produced 1600L/H

Nice :D

Now to polish it up?

bah! testing first, polishing second:p

now this is really bizzare, I don't get it at all.

what I was using previously was my 1/2'' fitting "carved out" block (which is my best performing block to date) with a small 700L/H pump (around 500L/H system flow) this is cooling a P4 1.8a@2.64, 1.8v, 11 degrees above water temp at idle and 14 degrees above under load.

now this new block, with my big 2800L/H pump up it's butt, pushing 3 times the flowrate of the previous setup, is getting exactly the same temps! (+- a degree or so)

I still have to muck around with the exact mounting of the block, but the P4's a far more forgiving in this area than the athlons...

Oh I'm using a pretty large volume of water in the system, so the larger pump putting more heat into the water isn't an issue at this stage.

Mabie the P4 simply isn't generating enough heat to show a difference? :shrug:

Interesting .
Maybe the flow is borderline laminar/turbulent.
For example:
50mm wide plate with 58fins and flow rate of 1600l/h:
1) 0.1mm thick x 8mm high :-- :Individual Channel size 0.78x8mm Flow Xsectional Area 354 sq.mm ,Velocity 1.26m/s,Characteristic dimension 1.5mm, Reynolds No 1841.
2) 0.2mm thick x 8mm high:-- Individual Channel size 0.67x8mm,Flow Xsectional Area 307 sq.mm ,Velocity 1.45m/s,Characteristic dimension 1.3mm, Reynolds No 1852

Reducing the fin height to 5mm for the 0.2mm case would increase the Reynolds to 2893 at a flow of 1600l/h but unfortunately with an increase in 3-4fold increase in "pump delivery head" requirements,

yup, certain paths only go so far
consider the thermal gradients involved
shorten the upstream length a bunch, downstream 1/2 as much
then boost the pressure/velocity

even so your gains will be quite slight

with a P4 you can also thin the bp, that will help more

BTW, you have a 'low flow' design; you need pressure, not volume

so you mean I should trim the fins more so they are mainly just over the core, say the size of the intel heatspreader, and force the water through that?

the bp is 4mm thick, little bit thinner now after I lapped it (had to lap quite a bit)

I can easily change the design, just add heat and it'll all fall apart...

and do you mean that I have a low flow volecity design?