PC case thumbscrews screw size
M4 · 5 to 8 mm long
Our records put PC case thumbscrews on M4 screws in lengths from 5 to 8 mm.
Where it is used: drive bay and expansion slot thumbscrews (US cases often 6-32 instead).
Head and drive, as the source states them: thumb screw (knurled) head.
This entry is marked reported and comes from makeuseof.com.
M4 means a 4 mm nominal diameter with a 0.7 mm thread pitch. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
PC case thumbscrews 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 |
|---|---|---|---|---|---|---|
| M4 | 5–8 mm | 0.7 mm | Thumb screw (knurled) | not stated | drive bay and expansion slot thumbscrews (US cases often 6-32 instead) | Reported |
Fitment records and sources
drive bay and expansion slot thumbscrews (US cases often 6-32 instead)
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
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 M4 screw measures about 4 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.7 mm from one thread crest to the next (14.29 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: for thumb screw (knurled) screws, measure from under the head to the tip (countersunk heads are the exception: they are measured overall).
- The records span 5–8 mm, which means different positions take different lengths — match each hole to its own screw.
- Driver: the source does not name the drive. Standard M4 heads take PH2 for Phillips and T20 for Torx, and a 3 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 M4 is about 2.0-3.0 N·m into metal threads and 0.8-1.4 N·m into plastic bosses; snug it up and stop.
Common mix-ups with M4
- Festo sensor brackets are named after the sensor interface (DASP-M4-...), but the bracket's own fixing screws are often a different size (M5/M6/M8).
- In EV charging part numbers 'M3'/'M4' often means IEC 61851 charging Mode 3/Mode 4, not a screw thread.
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Devices whose records share a thread with PC case thumbscrews, closest length match first.
- ASUS AIO M3700WUA/WYA all-in-one PC also M4 × 7 mm
- Dell Inspiron 27 7775 Aio also M4 × 6 mm
- Mini-PC VESA brackets (Intel NUC, Mac mini) also M4 × 8 mm
- Schneider Electric Box iPC Universal / Performance also M4 × 6 mm
- Mini PC / thin client VESA adapter kit also M4 × 8 mm
- Dell Inspiron 24 5475 Aio also M4 × 6 mm
- Hallde Blender SB-4 also M4 × 8 mm
- Elo EMV bracket pan-head screw (Bag P) also M4 × 5 mm
Questions about PC case thumbscrews screws
- What size screw does PC case thumbscrews use?
- M4 × 5–8 mm for drive bay and expansion slot thumbscrews (US cases often 6-32 instead).
- How long are the screws in PC case thumbscrews?
- The records range from 5 to 8 mm depending on the position, so match each screw to its own hole.
- What is the thread pitch of an M4 screw?
- 0.7 mm (coarse), which is the standard pitch for M4 machine screws; a 0.5 mm fine pitch exists but is uncommon. The tap drill is 3.3 mm and the normal clearance hole is 4.5 mm.
- What screwdriver do I need for PC case thumbscrews?
- The sources do not name the drive. For M4, Phillips heads normally take PH2 and Torx heads T20; socket heads take a 3 mm hex key.
- Can I use an imperial screw instead of M4?
- No. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same. Use a true M4 screw so it does not cross-thread or strip the hole.