Discussion Consistency of location of a cpu socket, relative to the board?

[msystems]

Wondering if there is there any kind of standards that dictate where the CPU socket itself is placed on x/y axis relative to the board (relative to the footprint of the atx/itx definition itself). Does each manufacturer just kind of do their own thing (even among the same socket) or do they adhere to any exact consistency?

Then the second thing is about consistency on the "Z" height of the package. Searching around it sounds like it's within a few mm, and within the current generation of Intel and AMD processors, it seems to be within the range of 7-8mm, which is great. But I suppose that the board flex could add some minor variation though.

Lets say I get standoffs in different lengths though. Assuming the worst, if I've got a few sets of different standoffs (lets say a 5mm, 6mm, & 7mm), would I be able to ensure the Z height of the CPU surface is within +/- 1mm, no matter the board and socket?

Im looking at designing "universal" fitting chassis integrated cooling (via heatpipe) and I have an idea of how to deal with sizeable x,y variations if I have to, but the Z height must be as consistent as possible.

 

[Gotmachine]

Does each manufacturer just kind of do their own thing (even among the same socket) or do they adhere to any exact consistency?

There is no specification for where the CPU socket should be, it's entirely the choice of the manufacturer.
In practice, for an "usual" ITX layout, a ±5 mm variance on each axes is almost guaranteed between various board models, but larger variance isn't uncommon, and then there are boards that use different layouts (for example boards using SO-DIMM memory slots).
The "common" variance is considerably higher for microATX / ATX boards, I would say up to ±15mm, and the "usual" placement is quite different between the 3 form factors, the socket being usually much further away from the rear I/O side as the form factor grow. On some microATX/ ATX boards where the first PCIe16x slot is at the second position, the socket is placed much closer to the PCIE slots (on the assumption that the first PCIe slot won't be used).

Then the second thing is about consistency on the "Z" height of the package.

Z distance from the bottom of the board to the top of the CPU IHS is affected by 2 factors :

• CPU socket specification. Height from the top of the board can vary from socket to socket :
  • LGA 115X and 12XX are 7.78±0.47 mm (source)
  • LGA 17XX is 7.03±0.5 mm (source)
  • SP3 is 8.96 mm (source)
  • AM3 is 8.49±0.57 mm (source)
  • Not sure about AM4, I think it's about 1mm shorter than AM3
  • AM5 will be 7.98±0.6 (source)
• Board PCB thickness, which is free to vary per the ATX spec, although to my knowledge, all boards are using the 1.57mm industry standard.

So I think you should plan from 7 to 9 mm socket height, and standoff height adjustement by increments of 0.5mm.

 

[msystems]

This is super helpful. Thanks for the excellent info!

 

[Mr Whippy]

Just in case you hadn't looked, the HDPlex cases are interesting in this regard. They've been around a while and utilise a system across many sockets from a universal mount.
Also they have a GPU kit, which obviously has a fair bit of variation scope dimensionally too.

Cheeers