GPU Project Block

[RalphW]

I've lined up some time on a three-axis CNC mill so I'm starting to put a design together to make a set of GPU blocks for a SLI set-up. I'd like to go with a design that will provide adequate cooling for a GPU since I won't have the luxury of testing different designs etc.

All mounting holes can hopefully be made into the bottom of the delrin top which will overhang the base like Swiftech's design. VR-Zone had a database of mounting hole dimensions for recent video cards but all the pictures seem to have been removed.
I have to try to keep the machining time down especially in the copper. Pins are about 3mm in height with 2.5mm spacing between the pins. The copper base is also 3mm. I had planned on using a 2mm endmill for the channels and would rather not go smaller than that for machining time purposes. Also my limited ability using Solidworks or any CAD program would mean that I have to keep the deign fairly simple.
Anyway, this is what I've got so far:

[Talcite]

That should be a very simple design. Why not do something more like a U shaped channel block? as it stands, you might have a lot of stagnant water. Try lengthening the path the water has to travel. How much are delrin blocks anyways?

[RalphW]

A GPU block would cost about $50.00ea. CDN, but this is not about the cost.

I could create a gap in centre of the pin grid and run a divider part way down the middle of the top section pocket.

[Talcite]

sounds good. Try to keep the water flowing onto the pins, not above them. Maybe you should try using deflector plates in the path of the flow exiting from the tube? or perhaps keep the height really low. That might help temperature a bit. I actually was wondering about an unmachined delrin block, i'm planning to use it for my setup.

[jman1310]

Originally Posted by Talcite

sounds good. Try to keep the water flowing onto the pins, not above them. Maybe you should try using deflector plates in the path of the flow exiting from the tube? or perhaps keep the height really low. That might help temperature a bit. I actually was wondering about an unmachined delrin block, i'm planning to use it for my setup.

i've got a couple 1"x1"x1.5" derlin blocks sitting around that i got for ebay for a project that got scrapped
let me know if your interested
they cost me $15 USD

jman

[RalphW]

You can get plastics such as delrin from US Plastics.
http://www.usplastic.com/catalog/pro...uct%5Fid=10652
$45.00 for a 12" x 12" x 1/2" piece

I found a local plastics supplier that sells offcuts for much cheaper.

I'll have to think about the divider?deflector plate a bit.

[JFettig]

You might also want to check mcmaster.com I usually buy my delrin from them. they do sell rectangular bars.

Jon

[RalphW]

I added a divider to the top section to channel the water more. This change also created less pins directly above the GPU core so I'm not sure about this trade-off.

[JFettig]

start milling!

Those radiuses on the inlet and outlets could be chamfered easily with the same effect.

Do you have the mounting holes in it yet?
Make sure you make a backplate for the back of the card.

The tapped holes in the copper plate will have to be done carefully because they arent very deep, so make sure you do a good job and get them started well, I suggest to always tap starting from the opposite side you plan on using so you have for sure good threads.

Jon

[RalphW]

The plan is for next week.

I'll put in a more tapered chamfer on those holes you're referring to.
I've put quite a few 4mm threads in 6mm and thicker copper. Maybe I'll practice on some 3mm first.

My current graphic card has two mounting holes at 45 deg. to the core.
I will drill and tap into the top after it's made.
I can make up a stainless steel backing plate for this card and another one when (if) I upgrade the graphic card. The top section hopefully has enough overhang to mount cards with the four hole square pattern.
I'm still looking for dimensions for GF7x00 cards.

[Colt357tw]

U shape flow path will give you more evenly distributed temperature, (less hot spot) however your flow may reduce by 1/6~1/4 depends on your inner design. Though I would try very hard to avoid inlet and outlet coming to base with 90 degree bends, maybe a little tilted entry and exit angle?

If your pump has plenty of head and spit out 100+L/Hr when no load, you should be pretty good shape. Just find a low resistance rad that fits two 120mm fans and you can easily handle 3~400W of heat.

Designing WB with less than 36L/hr flow would be a pain in the butt, specially total mass of WB and connecter (no liquid) is not allow to break 400g...

[jman1310]

Originally Posted by RalphW

I'm still looking for dimensions for GF7x00 cards.

did you check this thread?

jman

[RalphW]

Colt357

My pump is rated at 700 L/HR with 3.2M head (AquaXtreme 50Z-DC12 )
Rad is a dual fan heatercore so I should be OK with the waterflow.
I thought about angling the water flow tube where it meets up with the fitting inlet chamber. With a three axis CNC, I can't think of how to do this without using a tilting vise then I run the risk of these tubes not lining up.

jman
I did check that thread but I only see the question of 7800/7900 mounting hole dimensions being asked; no answers are given.
In any case, I already have the mounting dimensions of the graphic cards that I will be using.

[JFettig]

If it helps any, my 6600 has the same holes as the gf4 and FX cards.

I think the angle in the top should be just fine, theres not much around it unless you can tilt it up and just cut it at an angle, I really think its not something to be conserned about, it'll only aid in flow but might reduce the performance.

Tapping the 3mm plate wont be hard, the hardest part is getting the tap started, but like I said, make sure to start it from the bottom of the hole, flip the part upsidedown and start from the bottom side, that way you make sure you have good threads at the part that needs it.


What kind of mill do you have to make this on?
Oh, I see your using a cnc, you could easily angle the inlet, just set it flat, and get a ball end mill and ramp it in. preferably drill it beforehand so it can go strait down, but also out and around. You can even ramp a flat end mill if you want. If you need help programming, I have had lots of experience programming by hand.


Jon

[RalphW]

Thanks Jon

I measured my 6600 card as close as I could.

I'll be using a Haas VF-3 for the main components milling and a manual mini-mill for any future modifications.
I know someone who can post-process IGES drawings for the machine code.

I was going to use a 1/4" ballnose endmill for the top profile so if I understand correctly, that tool could be used to mill an angled hole with the part flat. I'm still not clear about this.

[RalphW]

Hopefully the last modifications I need to make:
I put a copper fin in as the divider since it seemed like a better solution than creating a gap in the pin grid for a top divider method especially since this area is directly above the gpu core.
I think I will manually drill the inlet/outlet hole at 45 degrees to the hose barb fitting holes. Maybe just use the CNC to mark the location of the hole.

[JFettig]

Looks better. about the holes for the inlet and outlet, do those on the cnc, you just move the x or y and z at the same time and it'll cut those no problem. works pretty good.

talk to the guy whos programming it, he will know how to do it Im sure.

Jon

[Talcite]

actually, if i'm interpreting that drawing correctly, a 3axis machine can't do it.. you'd need a 4 axis machine to do that one. The jets can be cut IF you remount the block manually at an angle. But then you'd have problems with precise angle, cut depth, and that stuff. Another way to cut it is to machine the block in 2 sections. However, it'd be a pain to mount precisely.

I'd say you're better off with a vertical jet. You'd be surprised how much turbulence helps a waterblock.

flow is a good thing to sacrifice for lower temperatures.

[RalphW]

I think I'll get an extra top made up just in case I screw up the drilling.

I agree with the previous posters that 90 degree bends in the top should be avoided if at all possible due to the restriction it would cause.
Turbulence around the pins is a different matter.

[JFettig]

Talcite, if I can make this:

he can do a simple 2 axis simultaneous motion command.

If you want max heat dissipation(only notice 1 degree at most) you would go strait down, but you also want max flow so your best off with the 45 degree one.

Jon

[Talcite]

Jon, i don't think its as simple as that for the waterblock. he has a 45 degree hole WITH material covering it. He can't cut it without remounting the block after the initial cut. Problem is, when you remount a block, it will be difficult to put it into the precise location that it was originally, plus tilt it at the angle needed.

If he has a strong pump, he can easily use a vertical mount for the jets. Its not a restrictive design.

[JFettig]

I just assumed he took my suggestion, I suggested to just do a straight down hole then add a taper similar to what he did.

Jon