Computer case screws

In turn, these thread standards define preferred size combinations that are based on generic units—some on the inch and others on the millimetre.

The #6-32 UNC screws are often found on 3.5" hard disk drives and the case's body to secure the covers.

#4-40 UNC thumb screws are often found on the ends of DVI, VGA, serial and parallel connectors.

Notwithstanding many exceptions, they are commonly used for securing the following devices:[2][3] M3 screws typically accept a #2 Phillips screwdriver tip.

The standoff provides a margin of space between the motherboard and the case to keep the multiple solder points below from grounding and short-circuiting.

Some standoffs use the M3 female thread (which faces the motherboard) instead of #6-32 UNC, and on a rare occasion a mixture of types can be used in the same case.

These fasteners are typically located on either side of D-subminiature connectors, such as on VGA, DVI, serial, parallel and legacy game controller ports.

The screws are typically thumbscrews, but may be slotted or Phillips drive, especially where permanent attachment is expected, or where the heads need to be lower-profile to save space.

A 5mm hex socket might still fit, however where tightening or removal is required, care needs to be taken to select a nut driver with a sufficiently small outer diameter, as clearance between the jackpost and subminiature connector D-shell is limited.

Occasionally the #4-40 hexagonal standoffs come loose when loosening the #4-40 screws to remove a cable, gender changer, or adapter.

This makes it more suitable for fastening larger parts and thicker materials requiring increased holding strength.

This makes it more suitable for fastening into smaller parts and thinner materials requiring good strength in a limited space.

Its size and fine thread make it appropriate for applications where a #6-32 UNC would be excessively bulky without providing any other benefits versus the smaller M3.