PC case fan mounting (120/140mm) screw size
M3 · 20 to 30 mm long
PC case fan mounting (120/140mm) takes M3 metric screws in lengths from 20 to 30 mm.
The record covers standard case fans mount with M3 machine screws.
This entry is marked confirmed and comes from graphicscardhub.com.
M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
PC case fan mounting (120/140mm) screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M3 | 20–30 mm | 0.5 mm | not stated | not stated | Standard case fans mount with M3 machine screws | Confirmed |
Fitment records and sources
Standard case fans mount with M3 machine screws
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- A screw that is even 1 mm too long in a laptop base can push into the keyboard, battery or a board trace, so match the length position by position.
- Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- The records span 20–30 mm, which means different positions take different lengths — match each hole to its own screw.
- Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
- Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M3
- Some sewing-machine screws are labeled with metric-looking but slightly nonstandard sizes (e.g. M3.3) that are not true ISO M3 and are not interchangeable with standard M3 hardware.
- PC cases mix M3 (fans, optical and 2.5in drives) with imperial 6-32 (3.5in drives, motherboard standoffs) - don't force one into the other.
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Devices whose records share a thread with PC case fan mounting (120/140mm), closest length match first.
- Pumpkin CubeSat Kit (PC/104 stack) also M3 × 25 mm
- PC watercooling radiator fan screws also M3 × 20–30 mm
- PC case & radiator fans also M3 × 20–30 mm
- PC case fan mounting screws (aftermarket kits) also M3 × 25–30 mm
- PC case and radiator fan mounting also M3 × 25–30 mm
- ISO 14581 hexalobular (Torx) countersunk screw also M3 × 20 mm
- Wurth Elektronik WA-SSTIE steel spacer stud also M3 × 20–30 mm
- FDM hotend and extruder mounts (general) also M3 × 20 mm
Questions about PC case fan mounting (120/140mm) screws
- What size screw does PC case fan mounting (120/140mm) use?
- M3 × 20–30 mm for standard case fans mount with M3 machine screws.
- How long are the screws in PC case fan mounting (120/140mm)?
- The records range from 20 to 30 mm depending on the position, so match each screw to its own hole.
- What is the thread pitch of an M3 screw?
- 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
- What screwdriver do I need for PC case fan mounting (120/140mm)?
- The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
- Can I use an imperial screw instead of M3?
- No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.