M/B and GPU I/O dimensions wanted!

[gimmethatITXboneless]

I've been poking around online, and many of the atx-spec case i/o dimensions have slight variations between them, anywhere from .1mm to eight or 9mm differences.

I'm looking for the dimensions for the case rear i/o. Motherboard spacing to the GPU slots, GPU attachment hole dimensions, etc.

If you have dimensions that have worked for you in a case or project, I'm interested. Where did you guys get them? Trial and error?

 

[Necere]

The official ATX specs are available on formfactors.org
Motherboards and PCIe card dimensions based on the specs are available as models here (FYI the M1 was designed using this model)
All this and more can be found in James' post, which can be found by following the 'resources' link at the top of the forum here