Usually, the standoff has a #6-32 UNC male thread on one end which screws into a threaded hole in the case or motherboard backplate and a #6-32 UNC female thread in the other end which accepts a screw to retain the motherboard. Less often, the standoff has a female thread in both ends and a second screw is used to attach it to the case. 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.
Version 2.1 of the ATX specification states that the length of standoffs needs to be at least 0.25 inches (6.4 mm), with their cross sections fitting within 0.40 by 0.40 inches (10 mm × 10 mm) square areas centered around each mounting hole on ATX motherboards.[3]
#4-40 UNC thumbscrews[edit]
Pairs of #4-40 UNC thumbscrews are used to fasten certain connectors to hardware ports. The screws are typically located on either side of D-subminiature connectors such as on VGA, serial, parallel and legacygame controller ports. They are also more recently used on DVI connectors. The typical length for a #4-40 screw used in PCs is 3/16 in (0.1875 inches (4.76 mm)).
Material[edit]
Steel is by far the most common material used, frequently with a plated or anodized finish. Other materials including brass, aluminum, nylon and various plastics are also used for applications with particular physical or aesthetic requirements.
Comparison[edit]
The #6-32 UNC is a thicker screw with a more coarse thread. This makes it more suitable for fastening larger parts and thicker materials requiring increased holding strength. Its larger size and coarse thread make it easier to work with during assembly, with less risk of cross threading. The integrated flange provides greater holding strength with less risk of pull through. The hex head makes it easier to work with during assembly with powered torque screwdrivers.
The M3 is a thinner screw with a finer thread than the #6-32 UNC. 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.
Gallery[edit]
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Close-up of a #6-32 UNC screw with a flanged hex/Phillips head, commonly provided in PC cases
Close-up of a #6-32 UNC screw with a Phillips pan head, commonly provided in PC cases
Thumbscrews from an ATX PC case
Example[edit]
A regular computer case may require/include[4]
- 9 thumb screw 6-32 × 6 mm for 2.5' drive tray, expansion slots
- 18 special thumb screw unknown size for side panel, 3.5' drive tray, psu bracket
- 0 hexagon screw 6-32 × 6 mm for psu
- 34 phillips screw 6-32 × 5 mm for motherboard, 3.5' harddisk tray
- 0 phillips screw M3 × 5 mm for 2.5' harddrive
- 16 screw kb5 × 10 mm for fan
- 8 standoff 6-32 × 6.5 + 4 mm for motherboard
- 1 positioning standoff 6-32 × 6.5 + 4 mm for motherboard
References[edit]
- ^ abRutter, Daniel Dan's Data - Letters 53, 'Screwed', 2006-02-26
- ^'2.5-inch Hard Disk Drives Installation Guide'(PDF). HGST. January 30, 2007. Archived from the original(PDF) on December 24, 2012. Retrieved November 16, 2014.
- ^'ATX Specification, Version 2.1: Section 3.4.2 Secondary (Bottom/Solder) Side Height Constraints'(PDF). formfactors.org. 2012-08-18. p. 18. Archived from the original(PDF) on 2016-08-17. Retrieved 2014-12-22.
- ^'H440 Manual'(PDF). Nzxt. Retrieved 2017-02-07.
External links[edit]
Tower 3 6 0 5 Inches
- McDonough, Andy The 11 Tools Every System Builder Should Own retrieved Nov 2, 2014 from crn.com
- Torres, Gabriel Everything You Need To Know About The Screws Used on The PC retrieved Jun 20, 2016 from hardwaresecrets.com