Cutout Dimensions for Dual GPU Slot? (And also a few other pieces of advice needed)

Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
0
The Main Issue that I Need Some Help With:

I'm working on a little project in Inventor right now for a flat case, and stuff's going pretty well, but I'm kind of butting my head up against how to model the dual-slot GPU slot on the back of the case. If anyone knows the proper dimensions (which I can't seem to find anywhere, unfortunately) or has a design for a slot they could share, I'd really love that.

Goals for it:

Crucial:
-simple to machine and can be made from the same part as the back of the case - IE it doesn't require another part of sheet metal to make
-no larger than necessary - the GPU's chamber is about 140mm x 280mm x 58mm, but this slot must fit on a rectangle that's 125mm x ~56mm in space and smaller is better (support is intended primarily for Nvidia reference cards and cards of similar proportion, if that matters)

Preferred:
-visually simple
-offers high stability - a GPU riser cable will be used in the case so the GPU will get most of its support at the backplate and none from the motherboard

Some things that make it a bit simpler:
-I'm not opposed to having the part of the slot that sticks out be at the very end of the piece of sheet metal. This would probably make it easier to manufacture, but I don't know for sure.
-I'll include a couple renders of the gpu/motherboard tray that the slot will have to be on for clarity.
-Don't worry about that fan mount - it's for GPU airflow and a dust filter, not an actual fan (though a very slim 120mm could fit)
-Sheet metal is 12 gauge aluminum, or about 2.05mm. I know it's thicker than normal and promise there's a reason, but I want to keep what the rest of the case looks like a surprise for now ;)




My ideal choice would be something like the DAN A4's design, which seems to involve just one bend and no stamping/perforations/extra-parts.

Some other stuff I could use help with:
-Is there anywhere to buy female-female 7mm or 1/4" motherboard standoffs in bulk?
-Does anyone sell good right-angle gpu power cable extensions?
-I've got a couple of OBJ files of the GPU and motherboard that Inventor only reads as being 266.66 INCHES (for the GPU) and 170 INCHES (for the motherboard) instead of millimeters. Does anyone know how to scale them down? I could upload the parts here if that helps - if I try to scale them down in Inventor they just end up deleting themselves for some reason.
 

msystems

Airflow Optimizer
Apr 28, 2017
277
439
I don't know the answer to your question, but it raises an issue - Is a large graphics card safely supported by the PCI slot only, and if not receiving any structural support from the PCI slot (due to a riser)?

I suppose if the card is positioned with the edge vertically, I'm sure it would be strong enough because that is the stronger orientation.

But when the card is horizontal and PCB parallel to the ground, that would put a strain on the card, and the PCI slot/ bracket.
 
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Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
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The plan as of now is to have a small support "cradle"/"arm" which attaches with dual-lock to the bottom of the tray, which will hold the card up from below, and also provide support during vertical mounting (the case is asymmetrical and would stand up only one direction) but it's a part that I could build using my at home tools easily so I'd want to have a prototype of the motherboard tray before finalizing the design for that part. Having more support at the GPU output slot would make things simpler, but it's definitely not intended to be the sole method of support.

The case is intended to be standing vertically at most times, but will have a separate stand made of bent wire for horizontal mounting (in this situation the GPU would intake air from below and the CPU would intake air from above). When the case is vertical the GPU would be vertical, and when the case is horizontal the GPU would also be horizontal.
 

Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
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Without spoiling the exterior design too much, the case is designed to be carried by hand without a bag (weather permitting of course), and to have replaceable parts that will be very hard to break and very easy to replace. Interior stability is definitely a priority, which is why I'm shunning stuff like tape or velcro in favor of 3m dual-lock and bolts.
 

phaelax

Caliper Novice
Jul 7, 2017
23
23
I just looked up these dimensions last night for a model I was doing. But when I pulled up the image to paste here, I noticed the dimensions are slightly different than others. With the inconsistent numbers I'm now realizing, I'm not positive I would be giving you the correct info.

Here is the one I used.


The first slot starts 6.35mm from the end of the IO panel. Each slot is 12.7mm wide and spaced 7.62mm apart.

There's some figures here as well which have different values:
https://smallformfactor.net/forum/t...nd-tribulations-of-designing-a-case.60/page-2

And another diagram shows even different numbers still. So my only suggestion would be to measure an existing case if you can. I'll do it myself tonight because I need to verify this myself as well and I'll post my own diagram. My measurements should be within half a millimeter.
 
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phaelax

Caliper Novice
Jul 7, 2017
23
23
After taking my own measurements (as close as I can get with a ruler and a former machinist's eye), this is what I came up with. I think each diagram I've found has been slightly different due to a non-standard slot size. What does seem to match up fairly closely, however, is the center of the slots in relation to the IO panel. So I probably should've measured from center, but that's harder to do with just eyeballs. So I think the image above and the one I just made are both correct.

 
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Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
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It's kind of relaxing to find out it seems non-standardized - I thought I must have been going crazy for awhile. Thanks so much for the help with finding a set that works!
 

Necere

Shrink Way Wielder
NCASE
Feb 22, 2015
1,702
3,195
Have you looked at the resources section here on the site? James has links to various resources that are useful in figuring this stuff out. Formfactors.org has the official specs for ATX motherboards. It's pretty much all round imperial measurements, so the PCI slots for example are 0.8" (20.32mm) center-to-center.

The relation of the PCI slot cutouts to the rear I/O on the back panel are not defined in the spec, so what you have to do is hunt down the PCI express card electromechanical specification and use that to extrapolate the relations. Unfortunately, that spec is paywalled by PCI-SIG, but luckily some of us have put together models based on the specs, which you can use as a basis for designing your case. Those are also available for download in the resources section.
 
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Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
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I'd looked around in a cursory way, but that model library is a godsend. Rooting around in it now.
 

phaelax

Caliper Novice
Jul 7, 2017
23
23
Wish I saw those resources last week, would've saved me a lot of research time. Thanks Necere. I really need to figure out how to use sketchup.
 
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Eli

Cable Smoosher
Original poster
Jul 22, 2017
8
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If it helps, I got that library to open up and be accurate/usable/disassemblable in Inventor so it should work in most environments that support the filetype